In the fourth Canto of the Astronomics Manilius gives a twice repeated outline of the dispositions and aptitudes which the various signs of the Zodiac determine in their natives. Those who are born under the influence of Gemini have a special vocation for music and the study of the sky. But what is an arid summary in astrological handbooks becomes in Manilius’ poem a fine description of the musical form of Antiquity. It is also an opportunity for the author to take his stand in the debate on the origin of discoveries: is astronomy a gift of the gods or the fruit of man’s inventiveness. [Summary, p. 411]