This book contains the "relics" that were saved from the lost treatises of Euclid , as well as the relevant testimonies of the ancient authors. The book specifically refers to the 5 lost mathematical works of Euclid entitled: " Pseudaria ", " On Divisions ", " Conic Elements ", " Surface Areas " and " Conclusions ". All the information on his two works in theoretical mechanics, with probable titles " On heavy and light bodies " and " On equilibria " are still included.