Mathematician Nikolaos Kastanis , Doctor of Mathematics of the Aristotle University of Thessaloniki, forewords.

The two treatises of Autolycus of Pitaneus that we present refer to the application of spherical geometry to astronomy. The first treatise "On a moving sphere" is the oldest surviving theoretical geometrical text. The second treatise, which is a work of spherical astronomy, is entitled "On the Ascendants and Wests" and consists of two books. This work is later than the first and is in turn the oldest astronomical work we have in our hands.