Placidus de Titis (or Titus) (1603-1668)

Italian astrologer, mathematician, and Roman Catholic monk, born at Perugia, Italy, into a prominent noble family. Little is known of his early life prior to his joining the Olivetian order around 1624 at age 21. He later became a reader of mathematics and physics at the University of Padua and then in 1657 was appointed professor of mathematics at the Milanese University in Pavia. He remained at Pavia for the rest of his life.

In Placidus's lifetime, astrology was still the proper concern of scholars and churchmen, and Placidus served as astrologer to a number of prominent political leaders, including Leopold William (1614-62), the archduke of Austria. In his studies he focused upon Claudius Ptolemy 's ancient astrological work the Tetrabiblos, and in it he believed he had discerned Ptolemy's lost method of "dividing houses." (In reading an astrology chart, one must not only divide the chart into the 12 astrological signs but also rotate the chart to account for the rotation of the earth during a 24-hour period. Astrological houses serve as a second division system that (among other functions) facilitates that rotation. Placidus published his findings in two volumes in 1650 and 1657.

The work of Placidus had little immediate impact on astrology, which was entering a period of decline even as he was writing. At the end of the eighteenth century, however, as the revival of astrology began in England, Manoah Sibley translated some writings of Placidus into English, and a second translation, by John Cooper, was published in 1814. R. C. Smith, better known under his pen name, Raphael, used Sibley's translation in his annual Raphael's Ephemeris, the most popular ephemeris for the next century. (An ephemeris provides the daily charts of the planets and is used by astrologers to quickly prepare a horoscope chart.) Raphael's Ephemeris is still published and is used by many astrologers in Great Britain. Through Raphael the Placidian system became the dominant system in astrolgy today.

Sources:

Baugnet, Michael. Introduction to Primum Mobile…. by Placidus de Titis. Translated by John Cooper. London: Davis and Dickson, 1814.

Brau, Jean-Louis, Helen Weaver, and Allan Edwards, eds. Larousse Encyclopedia of Astrology. New York: New American Library, 1982.

Holden, James H., and Robert A. Hughes. Astrological Pioneers of America. Tempe, Ariz.: American Federation of Astrologers, 1988.

Lewis, James L. The Astrology Encyclopedia. Detroit: Gale Research, 1994.

Placidus de Titus. Astronomy and Elementary Philosophy. Translated by Manoah Sibley. London: W. Justins, 1789.

——. A Collection of Thirty Remarkable Nativities. Translated by Manoah Sibley. London: W. Justins, 1789.