Astronomer Panagiota Preka-Papadimas , Associate Professor of the Physics Department of the University of Athens, forewords.

This book contains three astronomical works. The "Ἀαφορικὸ", which is the second work, after the "Phenomena" of Euclid , which refers to purely mathematical astronomy, since three algebraic propositions are applied to arcs of the zodiac. It is probably a part of a lost treatise, but it is very clear and detailed in its subject matter.

"To Arato's Phenomena", which is a commentary on Arato 's work "Phenomena and Signs". This treatise is divided into 10 paragraphs in which references are made to Aratos , but personal opinions of Eratosthenes are also included. At the end of the last paragraph there is a table with the names of all those (astronomers and non-astronomers) who dealt with Aratus ' much-discussed astronomical poem. Specifically, in the work composed by him by the great Eudoxos "Phenomena".

"On Everything" by Achilles Tatius , which is probably a part of a wider astronomical treatise by Achilles Tatius with the same title (or with the title "On the Sphere") and is the section that comments on Aratus . The treatise consists of 39 paragraphs in which all the astronomical topics touched upon by Aratos are presented.