Guido Bonatti (died between 1296 and 1300) was an

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

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

astrologer Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions ...

, who was the most celebrated

of the 13th century. Bonatti was advisor of

Frederick II, Holy Roman Emperor Frederick II (, , , ; 26 December 1194 – 13 December 1250) was King of Sicily from 1198, King of Germany from 1212, King of Italy and Holy Roman Emperor from 1220 and King of Jerusalem from 1225. He was the son of Emperor Henry VI, Holy Roman ...

Ezzelino da Romano III Ezzelino III da Romano (25 April 1194, Tombolo7 October 1259) was an Italian feudal lord, a member of the Ezzelini family, in the March of Treviso (in modern Veneto). He was a close ally of the emperor Frederick II ( r. 1220–1250), and rul ...

, Guido Novello da Polenta and

Guido I da Montefeltro Guido da Montefeltro (1223 – 29 September 1298) was an Italian military strategist and lord of Urbino. He became a friar late in life, and was condemned by Dante Alighieri in his ''Divine Comedy'' for giving false or fraudulent counsel. Bio ...

. He also served the communal governments of

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 ...

Siena Siena ( , ; traditionally spelled Sienna in English; ) is a city in Tuscany, in central Italy, and the capital of the province of Siena. It is the twelfth most populated city in the region by number of inhabitants, with a population of 52,991 ...

and

Forlì Forlì ( ; ; ; ) is a ''comune'' (municipality) and city in Emilia-Romagna, Northern Italy, and is, together with Cesena, the capital of the Province of Forlì-Cesena.The city is situated along the Via Emilia, to the east of the Montone river, ...

. His employers were all

Ghibellines The Guelphs and Ghibellines ( , ; ) were factions supporting the Pope (Guelphs) and the Holy Roman Emperor (Ghibellines) in the Italian city-states of Central Italy and Northern Italy during the Middle Ages. During the 12th and 13th centurie ...

(supporters of the

Holy Roman Emperor The Holy Roman Emperor, originally and officially the Emperor of the Romans (disambiguation), Emperor of the Romans (; ) during the Middle Ages, and also known as the Roman-German Emperor since the early modern period (; ), was the ruler and h ...

), who were in conflict with the

Guelphs The Guelphs and Ghibellines ( , ; ) were Political faction, factions supporting the Pope (Guelphs) and the Holy Roman Emperor (Ghibellines) in the Italian city-states of Central Italy and Northern Italy during the Middle Ages. During the 12th ...

(supporters of the

Pope The pope is the bishop of Rome and the Head of the Church#Catholic Church, visible head of the worldwide Catholic Church. He is also known as the supreme pontiff, Roman pontiff, or sovereign pontiff. From the 8th century until 1870, the po ...

), and all were excommunicated at some time or another. Bonatti's astrological reputation was also criticised in

Dante Dante Alighieri (; most likely baptized Durante di Alighiero degli Alighieri; – September 14, 1321), widely known mononymously as Dante, was an Italian Italian poetry, poet, writer, and philosopher. His ''Divine Comedy'', originally called ...

's ''

Divine Comedy The ''Divine Comedy'' (, ) is an Italian narrative poetry, narrative poem by Dante Alighieri, begun and completed around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature and one of ...

'', where he is depicted as residing in

hell In religion and folklore, hell is a location or state in the afterlife in which souls are subjected to punishment after death. Religions with a linear divine history sometimes depict hells as eternal destinations, such as Christianity and I ...

as punishment for his astrology. His most famous work was his ''Liber Astronomiae'' or 'Book of Astronomy', written around 1277. This remained a classic astrology textbook for two centuries.

Biography

Bonatti's dates of birth and death are unknown, the latter probably occurring between 1296 and 1300. In 1233 he is known as the winner of a dispute in

Bologna Bologna ( , , ; ; ) is the capital and largest city of the Emilia-Romagna region in northern Italy. It is the List of cities in Italy, seventh most populous city in Italy, with about 400,000 inhabitants and 150 different nationalities. Its M ...

with the friar Giovanni Schio from

Vicenza Vicenza ( , ; or , archaically ) is a city in northeastern Italy. It is in the Veneto region, at the northern base of the Monte Berico, where it straddles the Bacchiglione, River Bacchiglione. Vicenza is approximately west of Venice and e ...

, who maintained the non-scientific basis of astrology. He is probably the first

to have used the midpoints in astrology. He used it to refine the timing for the military campaigns for the Count of

Montefeltro Montefeltro is a historical and geographical region in northern Italy. It gave its name to the House of Montefeltro, Montefeltro family, who ruled in the area during the Middle Ages and the Renaissance. The mountainous region includes San Marino ...

Bonati announced to the count that he would repulse the enemy but would be wounded in the fray. The event transpired as Bonati had predicted, and the count, who had taken with him the necessary materials to staunch his wound in case the prophecy came true, became a devout adherent of astrology.Guido Bonati: Information and Much More from Answers.com
/ref> There is a tradition that Bonatti, towards the end of his life, took the friar's habit of the

Franciscan Order The Franciscans are a group of related organizations in the Catholic Church, founded or inspired by the Italian saint Francis of Assisi. They include three independent Religious institute, religious orders for men (the Order of Friars Minor bei ...

. This has been contested, as Bonatti expressed great disdain for Franciscans in his early period. However, the Franciscan Order, in the 1924 inaugural issue of its annual publication, ''Franciscan Studies'', lays claim to Fra Guido Bonatti: According to the uncorroborated account of the Italian historian

Ludovico Antonio Muratori Lodovico Antonio Muratori (21 October 1672 – 23 January 1750), commonly referred to in Latin as Muratorius, was an Italian Catholic priest, notable as historian and a leading scholar of his age, and for his discovery of the Muratorian fragmen ...

, Bonatti was murdered by robbers whilst returning from a study trip to Paris and other Italian cities, being set upon in or near Casena, with his body left upon the road. Evidence from various accounts establishes that Bonatti was in his eighties when he died.

References

External links

Complete "Liber Astronomiae" by Guido Bonatti, English translation by Robert ZollerEnglish translation of Bonatti's Liber Astronomiae
* ttp://www.skyscript.co.uk/bonatti.html The Life of Guido Bonattibr>"Anima astrologiae, Guido Bonatus by William Lilly, Student in Astrology"

Guidonis Bonati De Astronomia tractatus
(Latin)
Online Galleries, History of Science Collections, University of Oklahoma Libraries
High resolution images of works by Guido Bonatti in .jpg and .tiff format. {{DEFAULTSORT:Bonatti, Guido 13th-century births 1290s deaths People from Forlì Italian astrological writers Italian astrologers 13th-century astrologers 13th-century Italian mathematicians 13th-century Italian astronomers Court of Frederick II, Holy Roman Emperor