Named for 17th-century astrologer Placidus de Titis, it is thought the Placidus system was first mentioned about 13th century in Arab literature, but the first confirmed publication was in 1602 by Giovanni Antonio Magini (1555–1617) in his book "Tabulae Primi Mobilis, quas Directionem Vulgo Dicunt". The first documented usage is from Czech, 1627. Later it was popularized by the Catholic Church as an argument for Ptolemy's geocentric theory of the Solar System, in the campaign against the heliocentric theory. Placidus, a professor of mathematics, was named as its author to give it credibility to his contemporaries. Placidus remains the most popular system among English-speaking astrologers