Foreword by Professor Emeritus of the University of Athens Maro K. Papathanasiou .

The present book, which contains four short treatises, is divided into three parts. The first part contains the famous and very understandable astronomical work of Proclus "On the Sphere", which is a summary of his larger astronomical work entitled "Ὑποτypοσις Αστρονομικήν ῶποτεσης". It was thought appropriate to add figures of the Celestial sphere with the associated circles mentioned in the text.

The second part contains the work of Damianos "Chapters of Optical Matters". This is a small work on Geometrical Optics, but of a lower level than Euclid 's work "Optics - Mirrors".

The third part contains the works of Domninos "Introductory Arithmetic Handbook" and "Introductory Arithmetic Handbook (How to use word to word afelein)". These are two small arithmetic projects. The second of the aforementioned works of Domninus is of particular interest because it presents for the first time the theory of how we can extract from a given ratio of two numbers a ratio that is also given and find the remaining ratio.