Roman Calendar
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The Roman calendar was the
calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A calendar date, date is the designation of a single and specific day within such a system. A calendar is ...
used by the
Roman Kingdom The Roman Kingdom, also known as the Roman monarchy and the regal period of ancient Rome, was the earliest period of Ancient Rome, Roman history when the city and its territory were King of Rome, ruled by kings. According to tradition, the Roma ...
and
Roman Republic The Roman Republic ( ) was the era of Ancient Rome, classical Roman civilisation beginning with Overthrow of the Roman monarchy, the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establis ...
. Although the term is primarily used for Rome's pre-Julian calendars, it is often used inclusively of the
Julian calendar The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year (without exception). The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts ...
established by
Julius Caesar Gaius Julius Caesar (12 or 13 July 100 BC – 15 March 44 BC) was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in Caesar's civil wa ...
in 46 BC. According to most Roman accounts, their original calendar was established by their legendary first king
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
. It consisted of ten
month A month is a unit of time, used with calendars, that is approximately as long as a natural phase cycle of the Moon; the words ''month'' and ''Moon'' are cognates. The traditional concept of months arose with the cycle of Moon phases; such lunar mo ...
s, beginning in spring with March and leaving winter as an unassigned span of days before the next year. These months each had 30 or 31
day A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, ...
s and ran for 38 nundinal cycles, each forming a kind of eight-day
week A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are ofte ...
nine days counted inclusively in the Roman mannerand ending with religious rituals and a public market. This fixed calendar bore traces of its origin as an observational lunar one. In particular, the most important days of each monthits kalends, nones, and idesseem to have derived from the new moon, the first-quarter moon, and the full moon respectively. To a late date, the
College of Pontiffs The College of Pontiffs (; see ''collegium'') was a body of the ancient Rome, ancient Roman state whose members were the highest-ranking priests of the Religion in ancient Rome, state religion. The college consisted of the ''pontifex maximus'' an ...
formally proclaimed each of these days on the Capitoline Hill and Roman dating counted down inclusively towards the next such day in any month. (For example, the year-end festival of
Terminalia Terminalia may refer to: * Terminalia (festival) Terminalia () was an ancient Roman festival in honour of the god Terminus, who presided over boundaries. His statue was merely a stone or post stuck in the ground to distinguish between propert ...
on 23February was called , the 6th day before the March kalends.) Romulus's successor
Numa Pompilius Numa Pompilius (; 753–672 BC; reigned 715–672 BC) was the Roman mythology, legendary second king of Rome, succeeding Romulus after a one-year interregnum. He was of Sabine origin, and many of Rome's most important religious and political ins ...
was then usually credited with a revised calendar that divided winter between the two months of
January January is the first month of the year in the Julian calendar, Julian and Gregorian calendars. Its length is 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the No ...
and
February February is the second month of the year in the Julian calendar, Julian and Gregorian calendars. The month has 28 days in common years and 29 in leap years, with the February 29, 29th day being called the ''leap day''. February is the third a ...
, shortened most other months accordingly, and brought everything into rough alignment with the solar year by some system of intercalation. This is a typical element of
lunisolar calendar A lunisolar calendar is a calendar in many cultures, that combines monthly lunar cycles with the solar year. As with all calendars which divide the year into months, there is an additional requirement that the year have a whole number of mont ...
s and was necessary to keep the Roman religious
festivals A festival is an event celebrated by a community and centering on some characteristic aspect or aspects of that community and its religion or cultures. It is often marked as a local or national holiday, Melā, mela, or Muslim holidays, eid. A ...
and other activities in their proper
season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's axial tilt, tilted orbit around the Sun. In temperat ...
s. Modern historians dispute various points of this account. It is possible the original calendar was agriculturally based, observational of the seasons and stars rather than of the moon, with ten months of varying length filling the entire year. If this ever existed, it would have changed to the lunisolar system later credited to Numa during the kingdom or early Republic under the influence of the
Etruscans The Etruscan civilization ( ) was an ancient civilization created by the Etruscans, a people who inhabited Etruria in List of ancient peoples of Italy, ancient Italy, with a common language and culture, and formed a federation of city-states. Af ...
and of Pythagorean Southern Italian Greeks. After the establishment of the Republic,
year A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 Synodic day, solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) ...
s began to be dated by consulships but the calendar and its rituals were otherwise very conservatively maintained until the Late Republic. Even when the nundinal cycles had completely departed from correlation with the moon's phases, a pontiff was obliged to meet the
sacred king In many historical societies, the position of kingship carried a sacral meaning and was identical with that of a high priest and judge. Divine kingship is related to the concept of theocracy, although a sacred king need not necessarily rul ...
, to claim that he had observed the new moon, and to offer a sacrifice to Juno to solemnize each kalends. It is clear that, for a variety of reasons, the intercalation necessary for the system's accuracy was not always observed. Astronomical events recorded in
Livy Titus Livius (; 59 BC – AD 17), known in English as Livy ( ), was a Roman historian. He wrote a monumental history of Rome and the Roman people, titled , covering the period from the earliest legends of Rome before the traditional founding i ...
show the civil calendar had varied from the solar year by an entire season in and was still two months off in . By the or before, control of intercalation was given to the pontifex maximus butas these were often active political leaders like Caesarpolitical considerations continued to interfere with its regular application. Victorious in civil war, Caesar reformed the calendar in 46 BC, coincidentally making the year of his third consulship last for 446days. This new Julian calendar was an entirely solar one, influenced by the
Egyptian calendar The ancient Egyptian calendar – a civil calendar – was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an Egyptian intercalary month, intercalary month of five epagomenal days treated as outs ...
. In order to avoid interfering with Rome's religious ceremonies, the reform distributed the unassigned days among the months (towards their ends) and did not adjust any nones or ides, even in months which came to have 31days. The Julian calendar was designed to have a single leap day every fourth year by repeating February 24 (a doubled or ) but, following Caesar's assassination, the priests mistakenly added the bissextile () leap day every three years due to their inclusive counting. In order to bring the calendar back to its proper place, Augustus was obliged to suspend intercalation for one or two decades. At 365.25 days, the Julian calendar remained slightly longer than the solar year (365.24 days). By the 16th century, the date of Easter had shifted so far away from the vernal equinox that Pope Gregory XIII ordered a further correction to the calendar method, resulting in the establishment of the modern
Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian cale ...
.


History


Prehistoric calendar

The original Roman
calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A calendar date, date is the designation of a single and specific day within such a system. A calendar is ...
is usually believed to have been an observational
lunar calendar A lunar calendar is a calendar based on the monthly cycles of the Moon's phases ( synodic months, lunations), in contrast to solar calendars, whose annual cycles are based on the solar year, and lunisolar calendars, whose lunar months are br ...
whose months ended and began from the new moon. Because a lunar cycle is about 29.5 days long, such months would have varied between . Twelve such months would have fallen short of the solar year and, without adjustment, such a year would have quickly rotated out of alignment with the seasons in the manner of the
Islamic calendar The Hijri calendar (), also known in English as the Islamic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the Ramad ...
. Given the seasonal aspects of the calendar and its associated
religious Religion is a range of social- cultural systems, including designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relate humanity to supernatural ...
festivals A festival is an event celebrated by a community and centering on some characteristic aspect or aspects of that community and its religion or cultures. It is often marked as a local or national holiday, Melā, mela, or Muslim holidays, eid. A ...
, this was presumably avoided through some form of arbitrary curtailment or intercalation or through the suspension of the calendar during winter. Against this, Michels has argued that the early calendars used by Rome and its neighbors were more probably observational of seasonal markers in nature (the leafing of trees), animal behavior (the
migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
of birds), and the agricultural cycle (the ripening of
grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...
) combined with observation of
star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
s in the
night sky The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlig ...
. She considers that this more sensibly accounts for later legends of
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
's decimal year and the great irregularity in Italian month lengths recorded in Censorinus. Roman works on agriculture including those of Cato,
Varro Marcus Terentius Varro (116–27 BCE) was a Roman polymath and a prolific author. He is regarded as ancient Rome's greatest scholar, and was described by Petrarch as "the third great light of Rome" (after Virgil and Cicero). He is sometimes call ...
,
Vergil Publius Vergilius Maro (; 15 October 70 BC21 September 19 BC), usually called Virgil or Vergil ( ) in English, was an ancient Roman poet of the Augustan period. He composed three of the most famous poems in Latin literature: the ''Eclogues'' ...
,
Columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...
, and Pliny invariably date their practices based on suitable conditions or upon the rising of stars, with only occasional supplementary mention of the civil calendar of their times until the 4th or 5th century author Palladius.
Augury Augury was a Greco- Roman religious practice of observing the behavior of birds, to receive omens. When the individual, known as the augur, read these signs, it was referred to as "taking the auspices". "Auspices" () means "looking at birds". ...
, formal Roman ornithomancy, continued to be the focus of a prestigious dedicated priesthood until at least the end of the 4th century. Although most Roman festivals in the historical record were closely tied to the nundinal cycle of the later calendar, there remained several moveable feasts (, "proclaimed festivals") like the
Sementivae Sementivae, also known as Feriae Sementivae or Sementina dies (in the country called Paganalia), was a Roman festival of sowing. It was a type of '' feriae conceptivae'' r ''conceptae'' These free days were held every year, but not on certain or ...
that were dependent on local conditions. Michels suggests this was the original state of all ancient festivals, marking divisions between the seasons and occasions within them.


Legendary 10-month calendar

The Romans themselves usually described their first organized year as one with ten fixed months, a decimal division fitting general Roman practice. There were four months of "31" daysMarch, May, Quintilis, and Octobercalled "full months" () and six months of "30" daysApril, June, Sextilis, September, November, and Decembercalled "hollow months" (').. These "304" days made up exactly 38  nundinal cycles. The months were kept in alignment with the moon, however, by counting the new moon as the last day of the first month and simultaneously the first day of the next month. The system is usually said to have left the remaining two to three months of the year as an unorganized "winter", since they were irrelevant to the farming cycle.
Macrobius Macrobius Ambrosius Theodosius, usually referred to as Macrobius (fl. AD 400), was a Roman provincial who lived during the early fifth century, during late antiquity, the period of time corresponding to the Later Roman Empire, and when Latin was ...
claims the 10-month calendar was fixed and allowed to shift until the summer months were completely misplaced, at which time additional days belonging to no month were simply inserted into the calendar until it seemed things were restored to their proper place. Licinius Macer's lost history apparently similarly stated that even the earliest Roman calendar employed intercalation. Censorinus, '' The Natal Day''
Ch. XX
Later Roman writers usually credited this calendar to
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
, their legendary first king and
culture hero A culture hero is a mythological hero specific to some group (Culture, cultural, Ethnic group, ethnic, Religion, religious, etc.) who changes the world through invention or Discovery (observation), discovery. Although many culture heroes help with ...
, although this was common with other practices and traditions whose origin had been lost to them. Censorinus considered him to have borrowed the system from
Alba Longa Alba Longa (occasionally written Albalonga in Italian sources) was an ancient Latins (Italic tribe), Latin city in Central Italy in the vicinity of Lake Albano in the Alban Hills. The ancient Romans believed it to be the founder and head of the ...
, his supposed birthplace. Some scholars doubt the existence of this calendar at all, as it is only attested in late Republican and Imperial sources and supported only by the misplaced names of the months from September to December.. Rüpke also finds the coincidence of the length of the supposed "Romulan" year with the length of the first ten months of the Julian calendar to indicate that it is an interpretation by late Republican writers. Other traditions existed alongside this one, however.
Plutarch Plutarch (; , ''Ploútarchos'', ; – 120s) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo (Delphi), Temple of Apollo in Delphi. He is known primarily for his ''Parallel Lives'', ...
's ''
Parallel Lives * Culture of ancient Greece Culture of ancient Rome Ancient Greek biographical works Ethics literature History books about ancient Rome Cultural depictions of Gaius Marius Cultural depictions of Mark Antony Cultural depictions of Cicero ...
'' recounts that
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
's calendar had been solar but adhered to the general principle that the year should last for 360 days. Months were employed secondarily and haphazardly, with some counted as 20 days and others as 35 or more. Plutarch records that while one tradition is that Numa added two new months to a ten-month calendar, another version is that January and February were originally the last two months of the year and Numa just moved them to the start of the year, so that January (named after a peaceful ruler called
Janus In ancient Roman religion and myth, Janus ( ; ) is the god of beginnings, gates, transitions, time, duality, doorways, passages, frames, and endings. He is usually depicted as having two faces. The month of January is named for Janus (''Ianu ...
) would come before March (which was named for Mars, the god of war). Rome's 8-day week, the nundinal cycle, was shared with the
Etruscans The Etruscan civilization ( ) was an ancient civilization created by the Etruscans, a people who inhabited Etruria in List of ancient peoples of Italy, ancient Italy, with a common language and culture, and formed a federation of city-states. Af ...
, who used it as the schedule of royal audiences. It was presumably a part of the early calendar and was credited in Roman legend variously to
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
and
Servius Tullius Servius Tullius was the legendary sixth king of Rome, and the second of its Etruscan dynasty. He reigned from 578 to 535 BC. Roman and Greek sources describe his servile origins and later marriage to a daughter of Lucius Tarquinius Pri ...
.


Republican calendar

The attested calendar of the
Roman Republic The Roman Republic ( ) was the era of Ancient Rome, classical Roman civilisation beginning with Overthrow of the Roman monarchy, the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establis ...
was quite different. It had twelve months, already including
January January is the first month of the year in the Julian calendar, Julian and Gregorian calendars. Its length is 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the No ...
and
February February is the second month of the year in the Julian calendar, Julian and Gregorian calendars. The month has 28 days in common years and 29 in leap years, with the February 29, 29th day being called the ''leap day''. February is the third a ...
during the winter. According to Livy, it was Numa Pompilius, the second king of Rome who divided the year into twelve lunar months (History of Rome, I.19). Fifty days, says Censorinus, were added to the calendar and a day taken from each month of thirty days to provide for the two winter months: Januarius (January) and Februarius (February), both of which had 28 days (The Natal Day, XX). This was a lunar year of 354 days but, because of the Roman superstition about even numbers, an additional day was added to January to make the calendar 355 days long. Auspiciously, each month now had an odd number of days: Martius (March), Maius (May), Quinctilis (July), and October continued to have 31; the other months, 29, except for February, which had 28 days. Considered unlucky, it was devoted to rites of purification (februa) and expiation appropriate to the last month of the year. (Although these legendary beginnings attest to the venerability of the lunar calendar of the Roman Republic, its historical origin probably was the publication of a revised calendar by the Decemviri in as part of the
Twelve Tables The Laws of the Twelve Tables () was the legislation that stood at the foundation of Roman law. Formally promulgated in 449 BC, the Tables consolidated earlier traditions into an enduring set of laws.Crawford, M.H. 'Twelve Tables' in Simon Hornbl ...
, Rome's first code of law.) The inequality between the lunar year of 355 days and the
tropical year A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky – as viewed from the Earth or another celestial body of the Solar System – thus completing a full cycle of astronom ...
of 365.25 days led to a shortfall over four years of (10.25 × 4) = 41 days. Theoretically, 22 days were interpolated into the calendar in the second year of the four-year cycle and 23 days in the fourth. This produced an excess of four days over the four years in line with the normal one day excess over one year. The method of correction was to truncate February by five days and follow it with the intercalary month which thus commenced (normally) on the day after February 23 and had either 27 or 28 days. February 23 was the
Terminalia Terminalia may refer to: * Terminalia (festival) Terminalia () was an ancient Roman festival in honour of the god Terminus, who presided over boundaries. His statue was merely a stone or post stuck in the ground to distinguish between propert ...
and in a normal year it was ' Thus the dates of the festivals of the last five days of February were preserved on account of them being actually named and counted inclusively in days before the kalends of March; they were traditionally part of the celebration for the new year. There was occasionally a delay of one day (a being inserted between February 23 and the start of the ) for the purpose of avoiding a clash between a particular festival and a particular day of the week (see for another example). The Roman superstitions concerning the numbering and order of the months seem to have arisen from Pythagorean superstitions concerning the luckiness of
odd number In mathematics, parity is the property of an integer of whether it is even or odd. An integer is even if it is divisible by 2, and odd if it is not.. For example, −4, 0, and 82 are even numbers, while −3, 5, 23, and 69 are odd numbers. The ...
s.. These Pythagorean-based changes to the Roman calendar were generally credited by the Romans to
Numa Pompilius Numa Pompilius (; 753–672 BC; reigned 715–672 BC) was the Roman mythology, legendary second king of Rome, succeeding Romulus after a one-year interregnum. He was of Sabine origin, and many of Rome's most important religious and political ins ...
,
Romulus Romulus (, ) was the legendary founder and first king of Rome. Various traditions attribute the establishment of many of Rome's oldest legal, political, religious, and social institutions to Romulus and his contemporaries. Although many of th ...
's successor and the second of Rome's seven kings, as were the two new months of the calendar. Most sources thought he had established intercalation with the rest of his calendar. Although
Livy Titus Livius (; 59 BC – AD 17), known in English as Livy ( ), was a Roman historian. He wrote a monumental history of Rome and the Roman people, titled , covering the period from the earliest legends of Rome before the traditional founding i ...
's Numa instituted a lunar calendar, the author claimed the king had instituted a 19-year system of intercalation equivalent to the Metonic cycle centuries before its development by Babylonian and Greek astronomers.
Plutarch Plutarch (; , ''Ploútarchos'', ; – 120s) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo (Delphi), Temple of Apollo in Delphi. He is known primarily for his ''Parallel Lives'', ...
's account claims he ended the former chaos of the calendar by employing 12months totalling 354days—the length of the lunar and Greek years—and a biennial intercalary month of 22days called Mercedonius. According to Livy's Periochae, the beginning of the consular year changed from March to 1January in 153BC to respond to a rebellion in Hispania. Plutarch believed Numa was responsible for placing January and February first in the calendar;
Ovid Publius Ovidius Naso (; 20 March 43 BC – AD 17/18), known in English as Ovid ( ), was a Augustan literature (ancient Rome), Roman poet who lived during the reign of Augustus. He was a younger contemporary of Virgil and Horace, with whom he i ...
states January began as the first month and February the last, with its present order owing to the
Decemvirs The decemviri or decemvirs (Latin for "ten men") refer to official ten-man commissions established by the Roman Republic. The most important were those of the two decemvirates, formally the decemvirate with consular power for writing laws () w ...
. W. Warde Fowler believed the Roman priests continued to treat January and February as the last months of the calendar throughout the Republican period. According to the later writers Censorinus and Macrobius, to correct the mismatch of the correspondence between months and seasons due to the excess of one day of the Roman average year over the tropical year, the insertion of the intercalary month was modified according to the scheme: common year (355 days), leap year with 23-day February followed by 27-day Mercedonius (377 days), common year, leap year with 23-day February followed by 28-day Mercedonius (378 days), and so on for the first 16 years of a 24-year cycle. In the last 8 years, the intercalation took place with the month of Mercedonius only 27 days, except the last intercalation which did not happen. Hence, there would be a typical common year followed by a leap year of 377 days for the next 6 years and the remaining 2 years would sequentially be common years. The result of this twenty-four-year pattern was of great precision for the time: 365.25 days, as shown by the following calculation: \frac=\frac=365\tfrac The consuls' terms of office were not always a modern calendar year, but ordinary consuls were elected or appointed annually. The traditional list of Roman consuls used by the Romans to date their years began in 509 BC..


Flavian reform

Gnaeus Flavius, a secretary (''scriba'') to censor App. Claudius Caecus, introduced a series of reforms in 304 BC. Their exact nature is uncertain, although he is thought to have begun the custom of publishing the calendar in advance of the month, depriving the priests of some of their power but allowing for a more consistent calendar for official business.


Julian reform

Julius Caesar Gaius Julius Caesar (12 or 13 July 100 BC – 15 March 44 BC) was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in Caesar's civil wa ...
, following his
victory The term victory (from ) originally applied to warfare, and denotes success achieved in personal duel, combat, after military operations in general or, by extension, in any competition. Success in a military campaign constitutes a strategic vi ...
in his civil war and in his role as '' pontifex maximus'', ordered a reformation of the calendar in 46 BC. This was undertaken by a group of scholars apparently including the
Alexandria Alexandria ( ; ) is the List of cities and towns in Egypt#Largest cities, second largest city in Egypt and the List of coastal settlements of the Mediterranean Sea, largest city on the Mediterranean coast. It lies at the western edge of the Nile ...
n Sosigenes and the Roman M. Flavius. Its main lines involved the insertion of ten additional days throughout the calendar and regular intercalation of a single leap day every fourth year to bring the Roman calendar into close agreement with the solar year. The year 46 BC was the last of the old system and included three intercalary months, the first inserted in February and two more—' and '—before the kalends of December.


Later reforms

After Caesar's assassination,
Mark Antony Marcus Antonius (14 January 1 August 30 BC), commonly known in English as Mark Antony, was a Roman people, Roman politician and general who played a critical role in the Crisis of the Roman Republic, transformation of the Roman Republic ...
had Caesar's birth month Quintilis renamed
July July is the seventh month of the year in the Julian calendar, Julian and Gregorian calendars. Its length is 31 days. It was named by the Roman Senate in honour of Roman general Julius Caesar in 44 B.C., being the month of his birth. Before the ...
(') in his honor. After Antony's defeat at Actium,
Augustus Gaius Julius Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian (), was the founder of the Roman Empire, who reigned as the first Roman emperor from 27 BC until his death in A ...
assumed control of Rome and, finding the priests had (owing to their inclusive counting) been intercalating every third year instead of every fourth, suspended the addition of leap days to the calendar for one or two decades until its proper position had been restored. See Julian calendar#Leap year error, Julian calendar: Leap year error. In 8 BC, the plebiscite ''Lex Pacuvia de Mense Augusto'' renamed Sextilis August (month), August (') in his honor. In large part, this calendar continued unchanged under the Roman Empire. (Roman Egypt, Egyptians used the related Alexandrian calendar, which Augustus had adapted from Egyptian calendar, their wandering ancient calendar to maintain its alignment with Rome's.) A few emperors altered the names of the months after themselves or their family, but such changes were abandoned by their successors. Diocletian began the 15-year indiction cycles beginning from the AD 297 census; these became the required format for official dating under Justinian I, Justinian. Constantine the Great, Constantine formally established the 7-day
week A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are ofte ...
by making Sunday an official holiday in 321. Consular dating became obsolete following the abandonment of appointing nonimperial consuls in AD 541. The Roman method of numbering the days of the month never became widespread in the Hellenized eastern provinces and was eventually abandoned by the Byzantine Empire in Byzantine calendar, its calendar.


Days

Roman dates were inclusive counting, counted inclusively forward to the next one of three principal days within each month: * Kalends (' or '), the first day of each month. * Nones (' or '), the seventhday of "full months" and fifthday of hollow ones, 8days before the Ides in every month * Ides (', variously ' or '), the 15thday of "full months" and the 13thday of hollow ones, one day earlier than the middle of each month. These are thought to reflect a prehistoric lunar calendar, with the kalends proclaimed after the sighting of the first sliver of the new crescent moon a day or two after the new moon, the nones occurring on the day of the first-quarter moon, and the ides on the day of the full moon. The kalends of each month were sacred to Juno and the ides to Jupiter (planet), Jupiter. The day before each was known as its eve ('); the day after each (') was considered particularly unlucky. The days of the month were expressed in early Latin using the ablative of time, denoting points in time, in the contracted form "the 6thDecember Kalends" ('). In classical Latin, this use continued for the three principal days of the month. but other days were idiomatically expressed in the accusative case, which usually accusative of time, expressed a duration of time, and took the form "6th day before the December Kalends" ('). This anomaly may have followed the treatment of days in Ancient Greek language, Greek, reflecting the increasing use of such date phrases as an absolute phrase able to function as the object of another preposition,. or simply originated in a mistaken agreement of ' with the preposition ' once it moved to the beginning of the expression. In late Latin, this idiom was sometimes abandoned in favor of again using the ablative of time. The kalends were the day for payment of debts and the account books (') kept for them gave English its word ''
calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A calendar date, date is the designation of a single and specific day within such a system. A calendar is ...
''. The public Roman calendars were the ''fasti'', which designated the religious and legal character of each month's days. The Romans marked each day of such calendars with the letters: * F (''Glossary of ancient Roman religion#fasti, fastus'', "permissible") on days when it was legal to initiate action in the courts of civil law (', "allowed days") * C (''comitialis'') on ''fasti'' days during which the Roman people could hold Legislative assemblies of the Roman Republic, assemblies (') * N (''Glossary of ancient Roman religion#nefastus, nefastus'') on days when political and judicial activities were prohibited (') * NP (uncertain) on public holidays (''Glossary of ancient Roman religion#feria, feriae'') * QRCF (uncertain) on days when the "king" (''rex sacrorum'') could convene an assembly * EN (', an Old Latin, archaic form of ', "halved") on days when most political and religious activities were prohibited in the morning and evening due to religion in ancient Rome#Sacrifice, sacrifices being prepared or offered but were acceptable for a period in the middle of the day Each day was also marked by a letter from A to H to indicate its place within the nundinal cycle of market days.


Weeks

The nundinae were the market days which formed a kind of weekend in ancient Rome, Rome, Roman Italy, Italy, and some other parts of Roman territory. By Roman inclusive counting, they were reckoned as "ninth days" although they actually occurred every eighth day. Because the republican and Julian years were not evenly divisible into eight-day periods, fasti, Roman calendars included a column giving every day of the year a nundinal letter from A to H marking its place in the cycle of market days. Each year, the letter used for the markets would shift along the cycle. As a day when the city swelled with rural plebeians, they were overseen by the aediles and took on an important role in Roman legislation, which was supposed to be announced for three nundinal weeks (between ) in advance of its coming to a vote. The patricians and their Patronage in ancient Rome, clients sometimes exploited this fact as a kind of filibuster, since the tribunes of the plebs were required to wait another three-week period if their proposals could not receive a vote before dusk on the day they were introduced. Superstitions arose concerning the bad luck that followed a nundinae on the nones of a month or, later, on the January Kalends, first day of January (Roman month), January. Intercalation was supposedly used to avoid such coincidences, even after the Julian reform of the calendar. The 7-day week began to be observed in Roman Italy, Italy in the early imperial period, as practitioners and converts to eastern religions introduced planetary hours, Hellenistic and Babylonian astrology, the Judaism in ancient Rome, Jewish Saturday Jewish sabbath, sabbath, and the Christianity in ancient Rome, Christian Lord's Day. The system was originally used for private worship and astrology but had replaced the nundinal week by the time Constantine I (emperor), Constantine made Sunday (') an official day of rest in AD 321. The hebdomadal week was also reckoned as a cycle of letters from A to G; these were adapted for Christian use as the dominical letters.


Months

The names of Roman months originally functioned as adjectives (e.g., the January kalends occur in the January month) before being treated as substantive nouns in their own right (e.g., the kalends of January occur in January). Some of their etymologies are well-established: January and March honor the gods Janus (god), Janus and Mars (god), Mars; July and August honor
Julius Caesar Gaius Julius Caesar (12 or 13 July 100 BC – 15 March 44 BC) was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in Caesar's civil wa ...
and his successor, the list of Roman emperors, emperor
Augustus Gaius Julius Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian (), was the founder of the Roman Empire, who reigned as the first Roman emperor from 27 BC until his death in A ...
; and the months Quintilis, Sextilis, September,. October, November, and December are archaic adjectives formed from the ordinal numeral, ordinal numbers from , their position in the calendar when it began around the spring equinox in March. Others are uncertain. February may derive from the Lupercalia, Februa festival or its eponymous ' ("purifications, expiatory offerings"), whose name may be either Sabine language, Sabine or preserve an archaic word for sulphuric. April may relate to the Etruscans, Etruscan goddess Apru or the verb ' ("to open"). May and June may honor Maia (goddess), Maia and Juno or derive from archaic terms for "senior" and "junior". A few list of Roman emperors, emperors attempted to add themselves to the calendar after Augustus, but without enduring success. In classical Latin, the days of each month were usually reckoned as: Dates after the ides count forward to the kalends of the next month and are expressed as such. For example, March 19 was expressed as "the 14th day before the April Kalends" ('), without a mention of March itself. The day after a kalends, nones, or ides was also often expressed as the "day after" (') owing to their special status as particularly unlucky "black days". The anomalous status of the new 31-day months under the Julian calendar was an effect of Caesar's desire to avoid affecting the
festivals A festival is an event celebrated by a community and centering on some characteristic aspect or aspects of that community and its religion or cultures. It is often marked as a local or national holiday, Melā, mela, or Muslim holidays, eid. A ...
tied to the nones and ides of various months. However, because the dates at the ends of the month all counted forward to the next kalends, they were all shifted by one or two days by the change. This created confusion with regard to certain anniversaries. For instance,
Augustus Gaius Julius Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian (), was the founder of the Roman Empire, who reigned as the first Roman emperor from 27 BC until his death in A ...
's birthday on the 23rdday of September was ' in the old calendar but ' under the new system. The ambiguity caused honorary festivals to be held on either or both dates.


Intercalation

The Republican calendar only had 355days, which meant that it would quickly unsynchronize from the solar year, causing, for example, agricultural festivals to occur out of season. The Roman solution to this problem was to periodically lengthen the calendar by adding extra days ''within'' February. February was broken into two parts, each with an odd number of days. The first part ended with the Terminalia on the 23rd ('), which was considered the end of the religious year; the five remaining days beginning with the Regifugium on the 24th (') formed the second part; and the intercalary month Mercedonius was inserted between them. In such years, the days between the ides and the Regifugium were counted down to either the Intercalary Kalends or to the Terminalia. The intercalary month counted down to nones and ides on its 5th and 13th day in the manner of the other short months. The remaining days of the month counted down towards the March Kalends, so that the end of Mercedonius and the second part of February were indistinguishable to the Romans, one ending on ' and the other picking up at ' and bearing the normal festivals of such dates. Apparently because of the confusion of these changes or uncertainty as to whether an intercalary month would be ordered, dates after the February ides are attested as sometimes counting down towards the Quirinalia (February 17), the Feralia (February 21), or the Terminalia (February 23) rather than the intercalary or March kalends. The third-century writer Censorinus says:
When it was thought necessary to add (every two years) an intercalary month of , so that the civil year should correspond to the natural (solar) year, this intercalation was in preference made in February, between the Terminalia [23rd] and Regifugium [24th].Censorinus, ''The Natal Day'', 20.28, tr. William Maude, New York 1900, available a

The fifth-century writer
Macrobius Macrobius Ambrosius Theodosius, usually referred to as Macrobius (fl. AD 400), was a Roman provincial who lived during the early fifth century, during late antiquity, the period of time corresponding to the Later Roman Empire, and when Latin was ...
says that the Romans intercalated in alternate years; the intercalation was placed after February 23 and the remaining five days of February followed. To avoid the nones falling on a nundine, where necessary an intercalary day was inserted "in the middle of the Terminalia, where they placed the intercalary month". This appears to have been generally correct. In 170BC, Mercedonius, Intercalaris began on the second day after February 23 and, in 167BC, it began on the day after February 23.
Varro Marcus Terentius Varro (116–27 BCE) was a Roman polymath and a prolific author. He is regarded as ancient Rome's greatest scholar, and was described by Petrarch as "the third great light of Rome" (after Virgil and Cicero). He is sometimes call ...
, writing in the first centuryBC, says "the twelfth month was February, and when intercalations take place the five last days of this month are removed."Varro, ''On the Latin language'', 6.13, tr. Roland Kent, London 1938, available a

Since all the days after the Ides of Intercalaris were counted down to the beginning of March, the month had either 27days (making 377 for the year) or 28 (making 378 for the year). There is another theory which says that in intercalary years February had and Intercalaris had 27. No date is offered for the Regifugium in 378-day years. Macrobius describes a further refinement whereby, in one 8-year period within a 24-year cycle, there were only three intercalary years, each of 377days. This refinement brings the calendar back in line with the seasons and averages the length of the year to 365.25days over 24years. The Pontifex Maximus determined when an intercalary month was to be inserted. On average, this happened in alternate years. The system of aligning the year through intercalary months broke down at least twice: the first time was during and after the Second Punic War. It led to the reform of the 191 BC Acilian Law on Intercalation, the details of which are unclear, but it appears to have successfully regulated intercalation for over a century. The second breakdown was in the middle of the first century BC and may have been related to the increasingly chaotic and adversarial nature of Roman politics at the time. The position of Pontifex Maximus was not a full-time job; it was held by a member of the Roman elite, who would almost invariably be involved in the machinations of Roman politics. Because the term of office of elected Magistratus ordinarii / extraordinarii, Roman magistrates was defined in terms of a Roman calendar year, a Pontifex Maximus had an incentive to lengthen a year in which he or his allies were in power or shorten a year in which his political opponents held office. Although there are many stories to interpret the intercalation, a period of is always synodic month short. Obviously, the month beginning shifts forward (from the new moon, to the third quarter, to the full moon, to the first quarter, back the new moon) after intercalation.


Years

As mentioned above, Rome's legendary 10-month calendar notionally lasted for 304days but was usually thought to make up the rest of the solar year during an unorganized winter period. The unattested but almost certain lunar year and the pre-Julian civil year were long, with the difference from the solar year more or less corrected by an irregular intercalary month. The Julian calendar, Julian year was 365days long, with a leap day doubled in length every fourth year, almost equivalent to the present Gregorian calendar, Gregorian system. The calendar era before and under the Roman Kingdom, Roman kings is uncertain but dating by regnal years was common in antiquity. Under the
Roman Republic The Roman Republic ( ) was the era of Ancient Rome, classical Roman civilisation beginning with Overthrow of the Roman monarchy, the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establis ...
, from 509 BC, years were most commonly described in terms of their reigning Roman consul, ordinary consuls. (Suffect consul, Temporary and honorary consuls were sometimes elected or appointed but were not used in dating.) List of Roman consuls, Consular lists were displayed on the fasti, public calendars. After the institution of the Roman Empire, regnal dates based on the emperors' terms in office became more common. Some historians of the later republic and early imperial eras dated from the legendary founding of the city of Rome (' or ).
Varro Marcus Terentius Varro (116–27 BCE) was a Roman polymath and a prolific author. He is regarded as ancient Rome's greatest scholar, and was described by Petrarch as "the third great light of Rome" (after Virgil and Cicero). He is sometimes call ...
's date for this was 753 BC but other writers used different dates, varying by several decades. Such dating was, however, never widespread. After the consuls waned in importance, most Roman dating was regnal. or followed Diocletian's 15-year Indiction tax cycle. These cycles were not distinguished, however, so that "year 2 of the indiction" may refer to any of 298, 313, 328, &c. The Greek Orthodox Church, Orthodox subjects of the Byzantine Empire used various Christian eras, including Anno Martyrum, those based on Diocletian's persecutions, Incarnation (Christianity), Christ's incarnation, and Anno Mundi, the supposed age of the world. The Romans did not have records of their early calendars but, like modern historians, assumed the year originally began in March on the basis of the names of the months following June. The consul Marcus Fulvius Nobilior (consul 189 BC), M. Fulvius Nobilior (r. 189 BC) wrote a commentary on the calendar at his Temple of Hercules Musarum that claimed January had been named for Janus (god), Janus because the god faced both ways, suggesting it had been instituted as a first month. It was, however, usually said to have been instituted along with February, whose nature and festivals suggest it had originally been considered the last month of the year. The consuls' term of office—and thus the order of the years under the republic—seems to have changed several times. Their inaugurations were finally moved to January 1(') in 153BC to allow Quintus Fulvius Nobilior, Q. Fulvius Nobilior to attack Segeda in Prehistoric Spain, Spain during the Celtiberian Wars, before which they had occurred on March 15 ('). There is reason to believe the inauguration date had been May 1 during the until 222BC and
Livy Titus Livius (; 59 BC – AD 17), known in English as Livy ( ), was a Roman historian. He wrote a monumental history of Rome and the Roman people, titled , covering the period from the earliest legends of Rome before the traditional founding i ...
mentions earlier inaugurations on May 15 ('), July 1 ('), August 1 ('), October 1('), and December 15 ('). Under the Julian calendar, the year began on January 1 but years of the Indiction cycle began on September 1. In addition to Egyptian calendar, Egypt's separate calendar, some provinces maintained their records using a local era. Africa (Roman province), Africa dated its records sequentially from 39BC; Roman Spain, Spain from AD38. This dating system continued as the Spanish era used in medieval Spain.


Conversion to Julian or Gregorian dates

The continuity of names from the Roman to the
Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian cale ...
can lead to the mistaken belief that Roman dates correspond to Julian or Gregorian ones. In fact, the essentially complete list of Roman consuls allows general certainty of years back to expulsion of Tarquin, the establishment of the
Roman Republic The Roman Republic ( ) was the era of Ancient Rome, classical Roman civilisation beginning with Overthrow of the Roman monarchy, the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establis ...
but the uncertainty as to the end of lunar dating and the irregularity of Roman intercalation means that dates which can be independently verified are invariably weeks to months outside of their "proper" place. Two astronomical events dated by
Livy Titus Livius (; 59 BC – AD 17), known in English as Livy ( ), was a Roman historian. He wrote a monumental history of Rome and the Roman people, titled , covering the period from the earliest legends of Rome before the traditional founding i ...
show the calendar four months out of alignment with the Julian date in 190BC and two months out of alignment in 168BC. Thus, "the year of the consulship of Publius Cornelius Scipio Africanus and Publius Licinius Crassus Dives (consul 205 BC), Publius Licinius Crassus" (usually given as "205BC") actually began on March 15, 205BC, and ended on March 14, 204 BC, according to the Roman calendar but may have begun as early as November or December 206BC owing to its misalignment. Even following the establishment of the
Julian calendar The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year (without exception). The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts ...
, the leap years were not applied correctly by the Roman priests, meaning dates are a few days out of their "proper" place until a few decades into Augustus's reign. Given the paucity of records regarding the state of the calendar and its intercalation, historians have reconstructed the correspondence of Roman dates to their Julian and Gregorian equivalents from disparate sources. There are detailed accounts of the decades leading up to the Julian reform, particularly the speeches and letters of Cicero, which permit an established chronology back to about 58BC. The nundinal cycle and a few known synchronisms—e.g., a Roman date in terms of the Attic calendar and Olympiad—are used to generate contested chronologies back to the start of the First Punic War in 264BC. Beyond that, dates are roughly known based on clues such as the dates of harvests and seasonal Roman festivals, religious festivals.


See also

* List of calendars * Julian calendar, Julian, Alexandrian calendar, Alexandrian, Byzantine calendar, Byzantine, &
Gregorian calendar The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian cale ...
s * Fasti, menologia rustica, and the Calendar of 354 * List of Roman consuls and ''ab urbe condita'' dating * General Roman Calendar of the Catholic Church * Roman festivals * Undecimber


Notes


References


Citations


Modern sources

* * * * * * * * * * * * * * * * * * *


Ancient sources

* * * * * * , anonymous translation. * * * * * * * * * * * * * * *


External links


Chris Bennett's reconstruction of early Roman dates
in terms of the Julian calendar
Roman Date Calculator
The North American Institute of Living Latin Studies * {{Authority control Roman calendar, Calendars Culture of ancient Rome, Calendar Time in Italy