530 
COMMENTATORS AND BYZANTINES 
number of books which he wrote, including a large number of 
commentaries, mostly on the dialogues of Plato (e.g. the 
Timaeus, the Republic, the Parmenides, the Gratylus). He 
was an acute dialectician and pre-eminent among his contem 
poraries in the range of his learning; he was a competent 
mathematician ; he was even a poet. At the same time he 
was a believer in all sorts of myths and mysteries, and 
a devout worshipper of divinities both Greek and Oriental. 
He was much more a philosopher than a mathematician. In 
his commentary on the Timaeus, when referring to the ques 
tion whether the sun occupies a middle place among the 
planets, he speaks as no real mathematician could have 
spoken, rejecting the view of Hipparchus and Ptolemy because 
o Oeovpyos (sc. the Chaldean, says Zeller) thinks otherwise, 
‘ whom it is not lawful to disbelieve Martin observes too, 
rather neatly, that ‘ for Proclus the Elements of Euclid had 
the good fortune not to be contradicted either by the Chaldean 
Oracles or by the speculations of Pythagoreans old and new ’. 
Commentary on Euclid, Book I. 
For us the most important work of Proclus is his commen 
tary on Euclid, Book I, because it is one of the main sources 
of our information as to the history of elementaiy geometry. 
Its great value arises mainly from the fact that Proclus had 
access to a number of historical and critical works which are 
now lost except for fragments preserved by Proclus and 
others. 
(a) Sources of the Commentary. 
The historical work the loss of which is most deeply to be 
deplored is the History of Geometry by Eudemus. There 
appears to be no . reason to doubt that the work of Eudemus 
was accessible to Proclus at first hand. For the later writers 
Simplicius and Eutocius refer to it in terms such as leave no 
doubt that they had it before them. Simplicius, quoting 
Eudemus as the best authority on Hippocrates’s quadratures 
of lunes, says he will set out what Eudemus says ‘ word for 
word ’, adding only a little explanation in the shape of refer 
ences to Euclid’s Elements ‘owing to the memorandum-like 
style of Eudemus, who sets out his explanations in the abbre