Marcus Manilius, who lived in the reigns of Augustus and Tiberius, is the author of the earliest treatise on astrology we possess. His "Astronomica, " a Latin didactic poem in five books, begins with an account of celestial phenomena, and then proceeds to treat of the signs of the zodiac and the twelve temples; there follow instructions for calculating the horoscoping degree, and details of chronocrators, decans, injurious degrees, zodiacal geography, paranatellonta, and other technical matters. Besides exhibiting great virtuosity in rendering mathematical tables and diagrams in verse form, the poet writes with some passion about his Stoic beliefs and shows much wit and humour in his character sketches of persons born under particular stars. Perhaps taking a lead from Virgil in his "Georgics, " Manilius abandons the proportions of his last book to narrate the story of Perseus and Andromeda at considerable length. In spite of its undoubted elegance, the "Astronomica" is a difficult work, and this edition provides in addition to the first English prose translation a full guide to the poem, with copious explanatory notes and illustrative figures.