Treasury of Optics

FEDERICUS RISNERUS

...when Petrus Ramus had sought him out for a long time through various libraries, and having searched through all traces, finally found him offered at public auction and treated as if abandoned, he purchased him; and having later also obtained another copy, he handed both over to me (whom he had had as a companion and assistant in mathematical training for some years) to compare. Afterwards, when he had removed from his library some mathematical works dearer to him, and this Alhazen in particular, amidst the heat of the nascent wars, he took me with these as if they were his household gods to Basel, and spent an entire year occupied in restoring and conforming this author. I have discovered a diligence and learning in the Arab man that is truly admirable, and not at all, as far as I could observe, assisted by the ancient optics of Greece. There is almost nothing here of Euclid or Ptolemy. Perhaps he had taken something from Archimedes, Apollonius, and Auenellus, from whom it is testified by literary records that some works on optics were written; likewise from Damianus and others, whose books have not yet fallen into my hands. Yet Alhazen himself confesses the reading of ancient opticians in Book 6, Chapter 4, regarding the error that occurs in convex spherical mirrors, and in Book 7, Chapter 6, regarding how vision comprehends visible objects according to refraction. Therefore, having seen that he was a brilliant and copious writer on optics, but very confused, I took this advice with the persuasion and authority of P. Ramus: which is of this kind. First, because the whole work was divided into few and long chapters in a continuous and uninterrupted discourse, I divided the individual books and chapters into propositions; and I noted which theorems of Vitello responded to these, so that by a comparison of the theorems of both, the optical material would receive some light and clarity for the crude and novice reader. Next, I amended and restored all the demonstrations; I added their foundations and strengths (which were missing in many places) from Euclid, Theodosius, Apollonius, Serenus, and other geometers; but especially the fifth and sixth books, which contain catoptrics the study of reflection, and the seventh, which interprets refraction, I attempted to illustrate with certain small commentaries because of the obscurity and brevity of the demonstrations. Finally, I reconstructed the figures of all the propositions from the beginning. And here in matters and sentences...