Placidus de Titis (also ''de Titus'', Latinization of Placido de Titi, pseudonym ''Didacus Prittus Pelusiensis''; 1603–1668) was an

Olivetan The Olivetans, formally known as the Order of Our Lady of Mount Olivet, are a monastic order. They were founded in 1313 and recognised in 1344. They use the Rule of Saint Benedict and are a member of the Benedictine Confederation, where they ar ...

monk and professor of mathematics, physics and astronomy at the

University of Pavia The University of Pavia ( it, Università degli Studi di Pavia, UNIPV or ''Università di Pavia''; la, Alma Ticinensis Universitas) is a university located in Pavia, Lombardy, Italy. There was evidence of teaching as early as 1361, making it one ...

from 1657 until his death. Placidus popularized the system of

astrological houses Most horoscopic traditions of astrology systems divide the horoscope into a number (usually twelve) of houses whose positions depend on time and location rather than on date. In Hindu astrological tradition these are known as Bhāvas. The ho ...

now known as the " Placidian system", current in modern

astrology Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...

. He did not invent the method; it is acknowledged by the 12th century Hebrew astrologer Abraham Ibn Ezra as the system employed by

Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...

, an attribution that was accepted by Placidus.

Biography

Placidus was born in

Perugia Perugia (, , ; lat, Perusia) is the capital city of Umbria in central Italy, crossed by the River Tiber, and of the province of Perugia. The city is located about north of Rome and southeast of Florence. It covers a high hilltop and pa ...

, into the Titi noble family. His father died early, and he was looked after by his mother Cecilia. He studied at the

University of Padua The University of Padua ( it, Università degli Studi di Padova, UNIPD) is an Italian university located in the city of Padua, region of Veneto, northern Italy. The University of Padua was founded in 1222 by a group of students and teachers from ...

where his uncle Girolamo de Titi was professor of

theology Theology is the systematic study of the nature of the divine and, more broadly, of religious belief. It is taught as an academic discipline, typically in universities and seminaries. It occupies itself with the unique content of analyzing the ...

. One of his teachers was the astronomer

Andrea Argoli Andrea Argoli (1570–1657), born in Tagliacozzo, was a versatile Italian scholar. He was a jurist, mathematician, astronomer and astrologer, and medical writer. His father was Ottavio and his son, Giovanni. He was professor of mathematics at ...

. The Duchy of Milan at the time was owned by Habsburg Spain, administered by

Archduke Leopold Wilhelm of Austria Archduke Leopold Wilhelm of Austria (5 January 1614 – 20 November 1662), younger brother of Emperor Ferdinand III, was an Austrian soldier, administrator and patron of the arts. He held a number of military commands, with limited success, an ...

. The Archduke showed strong interest in science, especially occult sciences of

alchemy Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...

and astrology, and Placidus dedicated his astrological house tables to him. In 1657 he was appointed professor of mathematics at the

, a position he held for the rest of his life. Like his contemporary Jean-Baptiste Morin, Placidus opposed the copernican theory and retained a

geocentric In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, an ...

perspective, although there have been suggestions that he might have been a closet Copernican.Krafft, Fritz. “astrology.” in ''Brill's New Pauly: Encyclopedia of the Ancient World'', edited by Hubert Cancik et al., 3:985. Leiden: Brill, 2006. He died in Pavia in 1668.

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

translations of Placidus' ''Primum Mobile'' were published by Manoah Sibly (1789) and John Cooper (1814).

Works

* ''De motibus directionum coelestium mobilium'' (1641). * ''Physiomathematica sive coelestis philosophia'' (1650), Placidus'

magnum opus A masterpiece, ''magnum opus'' (), or ''chef-d’œuvre'' (; ; ) in modern use is a creation that has been given much critical praise, especially one that is considered the greatest work of a person's career or a work of outstanding creativity, ...

, first published as ''Quaestionum physiomathematicarum libri tres'', under the

pseudonym A pseudonym (; ) or alias () is a fictitious name that a person or group assumes for a particular purpose, which differs from their original or true name (orthonym). This also differs from a new name that entirely or legally replaces an individua ...

of Didacus Prittus Pelusiensis, second edition by C. Francobacci und A. Scirota (pseudonyms of two of Placidus' students, F. Brunacci and F. M. Onorati). * * ''Nuncius astronomicus'' (1654). * ''Il corriere astronomico'' (1656). * ''Tabulae primi mobilis cum thesibus et canonibus'' (1657). * ''Commentaria in Ptolemaeum de siderum judiciis'' (1658). * ''De siderum judiciis'', 2 vols. (1660, 1665). * * ''De diebus decretoriis et aegrorum decubitu'', 2 vols. (1661, 1665). * ''Ephemerides coelestium motuum'' (1661-1665). * * ''Tocco di paragone onde evidentemente appare che l’astrologia nelle parti concesse da S. Chiesa è vera scienza, naturale, nobile, et utile quanto la filosofia'' (1666), in defense of astrology as a

natural science Natural science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatab ...

. *

Biography

Works

Notes

Further reading