"The interests of Eratosthenes were remarkably diverse. He was a writer of philosophical dialogues, a poet, an astronomer, a geographer, a philologist, a chronicler, and a historian. These aspects of his work are, in fact, closely linked in the Alexandrian perception of intellectual training.

The variety of Eratosthenes' pursuits would impress us even more if we had access to more than just a few excerpts and two summaries: the Catasterisms and the On the Measurement of the Earth.

Overall, the surviving organization of the Summary of the Catasterisms is clear. It consists of two unequal parts: the first comprises 42 chapters, each dedicated to a constellation; the second successively describes the planets (chap. 43) and the Milky Way (chap. 44)." (From the introduction)