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(religion, spiritualism, and occult)

Placidus de Titis (1603–1668) was an Italian mathematician and astrologer best known for the house system that bears his name. He joined the Olivetan Order when he was 21. He was a reader of mathematics and physics at the University of Padua for some years, and he was appointed professor of mathematics at the Milanese University in Pavia in 1657, a position he held for the rest of his life. He was also an astrologer to some prominent religious and political figures of the time.

Placidus attributed the initial inspiration for his system of division to a remark made by Ptolemy in Tetrabiblos. Ptolemy equated different semidiurnal arcs because they are equivalent to the same number of temporary hours. Analogically, Placidus reasoned, the twelfth-house cusp should begin at one-third of the semidiurnal arc above the horizon, the eleventh-house cusp at two-thirds of the semidiurnal arc above the horizon, and so forth.

Although mistaken, Placidus was convinced he had discovered Ptolemy’s lost method of determining houses, and he began to write books in which he described the new system. This system was adopted by John Partridge but rejected by most other English astrologers. At the beginning of the revival of astrology in England in the late 18th century, Manoah Sibly published English translations of Placidus’s Primum Mobile. The system of Placidus became the dominant system in England, and later the Placidian system was passed to France and Germany. Beyond his house system, Placidus was the inventor of secondary and tertiary directions. He also promoted the use of transits to both the natal and the progressed positions of the planets.


Holden, James H., and Robert A. Hughes. Astrological Pioneers of America. Tempe, AZ: American Federation of Astrologers, 1988.
Placidus. Physiomathematica sive Coelestis Philosophia Naturalibus hucusque desideratis ostensa principiis [Physico-mathematical (questions) or Celestial Philosophy set forth by means of natural principles hitherto lacking …. ] 2d ed. [Revised by his pupils Brunaccio and Onorati from the 1650 edition.] Milan: Fran. Vigoni, 1675.
Placidus. Tabulae Primi Mobilis cum … Triginta clariss. natalium Thematibus. [Tables of the Primum Mobile with thirty horoscopes of famous births.] 2d ed. Milano: Fran. Vigoni, 1675. (Originally published 1657.)
References in periodicals archive ?
placidus was collected from lower sections of the Big Creek drainage and Hogthief Creek where they overlap slightly with O.
42) The volume has an eighteenth-century Scheyern provenance inscription, but it also bears the acquisition code q19 on the first flyleaf, marginal notes by Frater Placidus, and a Scheyern K30 binding.
placidus was the most frequently collected species (Table 1) during the course of this study, with specimens found throughout the drainage with the exception of the smallest tributaries (Fig.
22) Placidus goes one better, including his name and emphasizing his masculinity with the arbitrariness of the object: Placidus hie futuit quern voluit (Placidus fucked here whom he wished, CIL IV 2265), but his graffito lacks the humorous punch of the following: Scordopordonicus hic * bene / fuit * quern * voluit (Garliquefarticus fukt well here whom he wished, CIL IV 2188).
The writer, Placidus, seems to have attempted to improve the look of his opening greeting with an ornate script.
CAIUS JUNIUS FAUSTINUS PLACIDUS POSTUMIANUS probably governed Britannia during the reign of Emperor Caracalla.
36) If a corrupted gloss of Placidus has been correctly emended, the location of the corneta was remembered primarily as locus .
Probably we have read or heard the names Gessner, Scheuchzer, Euler, Placidus a Spescha, Kenngott, Wiser, Baumhauer, Ashcroft, Niggli, Parker and Graeser before, but this short chapter clarifies how these assorted mineralogists, mathematicians, Strahlers, savants and expatriates (e.
De todos modos si se utilizan otros sistemas de Casas desiguales como Placidus por ejemplo las diferencias muchas veces no son tan importantes.
Basta citar el epitafio que quiere llevar en su tumba Fernando para corroborado una vez mas, sin perder de vista que la ironia es un recurso mediante el que el autor desliza e instaura el juego entre la frase dicha en serio y la burla de una situacion determinada: "Vir clarisimus, grammaticus conspicuous, philologus, illustrisimus, quoque pius, placates, fraternus, placidus, unum et idem e pluribus unum, summum jus, hic natus atque mortuus est.