Tetrabiblos, or Quadripartite

The earliest surviving version of Tetrabiblos is the paraphrase attributed to Proclus the Philosopher (412-485 AD). Tetrabiblos (literally, "four books") was until recently thought to be a complete survey of Greek astrology. Modern research suggests this not to be the case, but Ptolemy's work remains the foundation of western astrology. In particular, his persuasive use of the Tropical Zodiac, rather than the Sidereal, changed astrology forever. Book 1 of Tetrabiblos defines various technical terms & supplies other information needed by the astrologer. Chapters 9, 10 & 11 detail the influence of fixed stars in various constellations. Book 2 is the astrology of nations & their rulers. Books 3 & 4 are devoted to natal astrology. Book 3, chapter 2, explains Ptolemy's method of rectifying the Ascendant. Chapter 10 gives a method for determining life expectancy. Book 4 deals with wealth, rank, employment, marriage, children, death, etc.

Published editions of Tetrabiblos traditionally include extracts from his Amalgest (a compendium of Greek astronomy), as well as "Ptolemy's Centiloquy," a list of aphorisms, the authorship of which is disputed. Many of the 100 deal with horary astrology. Like Tetrabiblos itself, these have been studied by astrologers for centuries.

Translations: Gardner (1911) listed four English translations of Tetrabiblos. The first was by John Walley, 1701. The second was Whalley's translation, as edited by Sibley & Brown, 1786, which is said to be worthless. The third, by James Wilson (author of the famous Dictionary of Astrology) was published in 1820. The fourth (this one, by far the best), was by J.M. Ashmand, first published in 1822. A fifth translation was made in 1940, by F.E. Robbins. Of these several translators, only Ashmand could claim to be both a Greek & Latin scholar as well as an experienced astrologer.

Ashmand's dedication is to Sir Walter Scott (1771-1832), author of Waverly, an historical novel about the Scots rebellion of 1745. To Ptolemy's text, Ashmand adds his own preface, as well as a note on Mr. Ranger's Zodiacal Planisphere.

Every serious astrologer, from the 3rd century to the present, has studied the Tetrabiblos. With the current revival of traditional astrology, it remains essential reading.