Procli Diadochi In Primum Euclidis Elementorum Librum Commentarii

(continues from previous page) page 354, 20 book III (IV), on folio 233 (below 433) book IV, though in truth it is the scholium of some uncertain person. On the contrary, on folio 109 (below 198), where even by Barocio’s judgment the ‘End of the Principles’ is found and the beginning of the propositions, not even the smallest note gives an indication of a new matter. When I saw these things, I no longer doubted that the division of the commentaries into four books originated from the copyist or scribe, whose exemplar was the source of all the copies we know. Barocio divided those individual books into chapters and commentaries, which Taylor followed, and I would have followed as well, had I not thought that the genuine form ought to be restored to Proclus’s work as much as possible. Proclus seems to me to have continued his commentaries in such a way that he would only interject the words of Euclid, but would distinguish his own very clearly arranged thoughts without any greater interval. Furthermore, it is by no means certain by what right Proclus’s work received the name of “commentaries”; you will say much more plausibly from the end of the first prologue (below 47, 7) that Proclus was going to write a study of mathematical discipline. But you will extract nothing certain from that. Therefore, I have retained the title handed down through three centuries, and I have added only six Latin inscriptions, and I have given Euclid’s definitions, postulates, axioms, and propositions their own numbers, to make a view of the whole work easier. So that individual things might be found more easily, I have added two indices, one of names and the other of subjects and words. Finally, in the upper part of each page, the page numbers of both Grynaeus and Barocio are placed, so that a longer delay might not hinder the reader looking for cited passages. The more people find pleasure in Proclus restored in Greek, the less I will regret the not insignificant labor consumed in this task.

Curia by the Saal, in the month of January in the year 1873.