Ignazio (or Egnazio) Danti, O.P. (April 1536 – 10 October 1586), born Pellegrino Rainaldi Danti, was an Italian Roman Catholic

prelate A prelate () is a high-ranking member of the Minister (Christianity), Christian clergy who is an Ordinary (church officer), ordinary or who ranks in precedence with ordinaries. The word derives from the Latin , the past participle of , which me ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

, and cosmographer, who served as Bishop of Alatri (1583–1586). ''(in Latin)''

Early life

Danti was born in

Perugia Perugia ( , ; ; ) is the capital city of Umbria in central Italy, crossed by the River Tiber. The city is located about north of Rome and southeast of Florence. It covers a high hilltop and part of the valleys around the area. It has 162,467 ...

in 1536 to a family of artists and scientists. As a boy he learned the rudiments of

painting Painting is a Visual arts, visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "Support (art), support"). The medium is commonly applied to the base with ...

and

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and construction, constructi ...

from his father Giulio, an architect and engineer who studied under Antonio da Sangallo, and his aunt Teodora,Brock, Henry. "Ignazio Danti." The Catholic Encyclopedia
Vol. 4. New York: Robert Appleton Company, 1908. 15 December 2022 who was said to have studied under the painter

Perugino Pietro Perugino ( ; ; born Pietro Vannucci or Pietro Vanucci; – 1523), an Italian Renaissance painter of the Umbrian school, developed some of the qualities that found classic expression in the High Renaissance. Raphael became his most famous ...

and also wrote a commentary on

Euclid Euclid (; ; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of geometry that largely domina ...

. His older brother Vincenzo Danti became one of the leading court sculptors of late-sixteenth-century Florence, while his younger brother Girolamo Danti (1547–1580) became a local painter. Danti entered the

Dominican Order The Order of Preachers (, abbreviated OP), commonly known as the Dominican Order, is a Catholic Church, Catholic mendicant order of pontifical right that was founded in France by a Castilians, Castilian priest named Saint Dominic, Dominic de Gu ...

on 7 March 1555, changing his baptismal name from ''Pellegrino'' to ''Ignazio''. After completing his studies in philosophy and theology he spent some time preaching but soon devoted himself zealously to mathematics, astronomy, and geography.

In Florence

In 1562, he requested a transfer from the Dominican compound in Perugia to the monastery of San Marco in

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

. Soon after, he found work on the side tutoring the children of wealthy Florentines in mathematics and science. In September 1563, he was invited by Cosimo I, Duke of Tuscany to participate in his cosmographical project, the Guardaroba in the

Palazzo Vecchio The ( "Old Palace") is the town hall of Florence, Italy. It overlooks the , which holds a copy of Michelangelo's ''David'' statue, and the gallery of statues in the adjacent Loggia dei Lanzi. Originally called the ''Palazzo della Signoria'', a ...

. Over the next dozen years, Danti painted 30 maps of regions of the world (based largely upon published prints by Giacomo Gastaldi,

Abraham Ortelius Abraham Ortelius (; also Ortels, Orthellius, Wortels; 4 or 14 April 152728 June 1598) was a cartographer, geographer, and cosmographer from Antwerp in the Spanish Netherlands. He is recognized as the creator of the list of atlases, first modern ...

Gerardus Mercator Gerardus Mercator (; 5 March 1512 – 2 December 1594) was a Flemish people, Flemish geographer, cosmographer and Cartography, cartographer. He is most renowned for creating the Mercator 1569 world map, 1569 world map based on a new Mercator pr ...

, and others) upon the cabinet doors of the Guardaroba. He also worked on many other significant scientific and cosmographic projects in Florence, including the large terrestrial

globe A globe is a spherical Earth, spherical Model#Physical model, model of Earth, of some other astronomical object, celestial body, or of the celestial sphere. Globes serve purposes similar to maps, but, unlike maps, they do not distort the surface ...

of the Guardaroba (1564–1568), and a number of brass scientific instruments (such as an astrolabe) today in the

Museo Galileo Museo Galileo (formerly ''Istituto e Museo di Storia della Scienza''; Institute and Museum of the History of Science) is located in Florence, Italy, in Piazza dei Giudici, along the River Arno and close to the Uffizi Gallery. The museum, dedicat ...

in Florence. Between 1567 and 1569,

Pius V Pope Pius V, OP (; 17 January 1504 – 1 May 1572), born Antonio Ghislieri (and from 1518 called Michele Ghislieri), was head of the Catholic Church and ruler of the Papal States from 7 January 1566 to his death, in May 1572. He was an ...

, who belonged to the Dominicans, is said to have commissioned Danti to furnish plans for the construction of a Dominican church and convent at

Bosco Marengo Bosco Marengo (; ) is a town and a ''comune'' (municipality) in the Province of Alessandria in the Italy, Italian region Piedmont, located about southeast of Turin and about southeast of Alessandria. Bosco Marengo borders the following municipa ...

Piedmont Piedmont ( ; ; ) is one of the 20 regions of Italy, located in the northwest Italy, Northwest of the country. It borders the Liguria region to the south, the Lombardy and Emilia-Romagna regions to the east, and the Aosta Valley region to the ...

; Danti acted mainly as an adviser. During his stay in

, Danti taught mathematics and published a number of scientific treatises, mostly commentaries on ancient and medieval astronomy and mathematics or explanations of how to use scientific instruments. For much of his time in Florence, Danti resided at the convent of

Santa Maria Novella Santa Maria Novella is a church in Florence, Italy, situated opposite, and lending its name to, the city's main railway station. Chronologically, it is the first great basilica in Florence, and is the city's principal Dominican church. The ch ...

, and designed the quadrant and the

armillary sphere An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines o ...

that appear on the end blind arches of the lower facade of the church in 1572 and 1574, on the right and left respectively. He also designed a large-scale

gnomon A gnomon (; ) is the part of a sundial that casts a shadow. The term is used for a variety of purposes in mathematics and other fields, typically to measure directions, position, or time. History A painted stick dating from 2300 BC that was ...

for the church which allowed a thin beam of light to enter the church at noon each day through a hole just beneath the facade's rose window, although it probably was not completed by the time Danti left Florence. In 1574, Danti used his instruments to calculate the time of the

March equinox The March equinox or northward equinox is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the ver ...

, an important date for calculating the

date of Easter As a moveable feast, the date of Easter is determined in each year through a calculation known as – often simply ''Computus'' – or as paschalion particularly in the Eastern Orthodox Church. Easter is celebrated on the first Sunday after the ...

. He discovered that it was 11 days out, falling on the 11 March rather than the 22 March, and he became a leading figure in proposing the reforms that lead to the adoption of 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 ...

in 1582. There were also discussions between the Duke and Danti about building a

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...

to place Florence in communication with both the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

and the

Adriatic The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkans, Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Se ...

. However, this ambitious plan was not started before Cosimo's death in 1574. In late September the following year, Cosimo's son, Grand Duke Francesco de' Medici, compelled Danti to leave Florence.O'Connor, John J, and Robertson, Edmund F., "Egnatio Pellegrino Rainaldi Danti", MacTutor, School of Mathematics and Statistics, University of St Andrews, Scotland, November 2002
/ref> It is not known precisely why Francesco exiled Danti, but the Dominican had no trouble finding work or patrons anywhere else in Italy, although he never returned to Florence.

Later life and bishopric

After leaving Florence, Danti became a professor of mathematics at the

University of Bologna The University of Bologna (, abbreviated Unibo) is a Public university, public research university in Bologna, Italy. Teaching began around 1088, with the university becoming organised as guilds of students () by the late 12th century. It is the ...

. He also spent some time in Perugia, at the invitation of the governor, where he prepared maps of the Perugian republic. 0 Italie - Corse - Sardaigne - Galleria delle carte geografiche

0 Italie - Corse - Sardaigne - Galleria delle carte geografiche

On account of his mathematical skills,

Pope Gregory XIII Pope Gregory XIII (, , born Ugo Boncompagni; 7 January 1502 – 10 April 1585) was head of the Catholic Church and ruler of the Papal States from 13 May 1572 to his death in April 1585. He is best known for commissioning and being the namesake ...

invited him to Rome, appointed him pontifical mathematician and made him a member of the commission for the reform of 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 ...

. He also placed him in charge of the painters whom the Pope had summoned to the

Vatican Vatican may refer to: Geography * Vatican City, an independent city-state surrounded by Rome, Italy * Vatican Hill, in Rome, namesake of Vatican City * Ager Vaticanus, an alluvial plain in Rome * Vatican, an unincorporated community in the ...

to continue the decoration of the palace, most notably to make a number of maps of the regions of modern Italy in the newly constructed Gallery of Maps along the

Cortile del Belvedere The (Belvedere Courtyard or Belvedere Court) was a major architectural work of the High Renaissance at the Vatican Palace in Rome. Designed by Donato Bramante from 1505 onward, its concept and details reverberated in courtyard design, formalize ...

. This project, begun in early 1580 and completed about 18 months later, mapped the entirety of the Italian peninsula in 40 large-scale frescoes, each depicting a region as well as a perspective view of its most prominent city. When the pontiff commissioned the architect Domenico Fontana to repair the Claudian harbour at

Portus Portus was a large artificial harbour of Ancient Rome located at the mouth of the Tiber on the Tyrrhenian Sea. It was established by Claudius and enlarged by Trajan to supplement the nearby port of Ostia. The archaeological remains of Portus a ...

, it was Danti who furnished the necessary plans. While at Rome Danti published a translation of a portion of

with annotations and wrote a life of the architect Jacopo Barozzi da Vignola, preparing also notes for the latter's work on perspective. In 1583, in recognition of his work, Gregory made him Bishop of Alatri in the Campagna. He was appointed on 14 November 1583, and

consecrated Sacred describes something that is dedicated or set apart for the service or worship of a deity; is considered worthy of spiritual respect or devotion; or inspires awe or reverence among believers. The property is often ascribed to objects (a ...

as bishop on 30 November 1583 by Giovanni Antonio Facchinetti de Nuce, Patriarch of Jerusalem. with Giovanni Battista Santorio, Bishop of Alife, and Gerolamo Mazzarelli, Bishop of Nona, serving as

co-consecrators A consecrator is a bishop who ordains someone to the episcopacy. A co-consecrator is someone who assists the consecrator bishop in the act of ordaining a new bishop. The terms are used in the canon law of the Catholic Church, Lutheran Churche ...

. Danti showed himself a zealous pastor in his new office. As Bishop of Alatri, Danti convoked a diocesan

synod A synod () is a council of a Christian denomination, usually convened to decide an issue of doctrine, administration or application. The word '' synod'' comes from the Ancient Greek () ; the term is analogous with the Latin word . Originally, ...

, corrected many abuses, and showed great solicitude for the poor. While bishop, he was the principal co-consecrator of Marco Pedacca, Bishop of Lacedonia (1584); and Basilio Gradi, Bishop of Stagno (1584). Shortly before his death

Pope Sixtus V Pope Sixtus V (; 13 December 1521 – 27 August 1590), born Felice Piergentile, was head of the Catholic Church and ruler of the Papal States from 24 April 1585 to his death, in August 1590. As a youth, he joined the Franciscan order, where h ...

summoned him to Rome to assist in the erection of the grand

Vatican obelisk The Vatican Obelisk is an List of Egyptian obelisks, Egyptian obelisk, one of the thirteen ancient List of obelisks in Rome, obelisks of Rome. This obelisk is located in St. Peter's Square, in Vatican City. It is the only ancient obelisk in Rome t ...

in the piazza of the Vatican. Besides the works already mentioned, Danti was the author of ''Trattato del'uso e della fabbrica dell'astrolabo con la giunta del planifero del Raja''; ''Le Scienze matematiche ridotte in tavole'', also a revised and annotated edition of ''La Sfera di Messer G. Sacrobosco tradotta da Pier Vincenzio Danti''. The first mentioned work deals with the use and construction of the astrolabe and is one of the oldest instructions for scientific instruments. Danti wrote the first Italian treatise on this topic to accompany the book.Ralf Kern, ''Wissenschaftliche Instrumente in ihrer Zeit'', Vol. 1, Cologne: Koenig, 2010, p. 318. Danti died at Alatri on 10 October 1586,"Bishop Ignazio (Pellegrino) Danti, O.P."
'' Catholic-Hierarchy.org''. David M. Cheney. Retrieved January 4, 2017 three years into his service.

Works

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References

External links and additional sources