On the Doctrines of Hippocrates and Plato, Vol. I

Medicine, having been cultivated by these men of such great authority, was transported to the Europeans along with philosophy. Once it was received, the foundation upon which the method of healing had been based by them up to that time was changed. They began to use not the simple method of the Greeks, but the perplexed method of the Arabs; not the sincere and true method of the former, but the faked and artificial one of the latter. Thus, they no longer directed their minds to what the Greeks had advised—that physicians should follow nature as the best teacher—but they wanted to apply to the exercise of the art precepts drawn solely from books, not from the contemplation and observation of nature. The vast and enormous commentaries of the Arabs, usually very poorly translated into Latin and therefore adapted more to obscuring than to illustrating matters, took the place of those books which they had previously used, derived from the School of Salerno. Galen, therefore, was removed from his kingdom by the physicians, but in such a way that it was not so much he himself who reigned, but foreign satraps who ordered the learned [to neglect] the mind.

the proof is that Ibn Abi Oseibia, the most famous author of the history of physicians among the Arabs in the 13th century, in his "Sources of Accounts of the Classes of Physicians," describes Johannitius telling of the fifteen books of Galen περὶ ἀποδείξεως On Demonstration—which are known to have perished now, except for one fragment—in this manner: "It did not befall any of our contemporaries to find a complete Greek copy of the work on demonstration, although Dschibril (Ben Bokht Jeschu) had greatly exhorted men to investigate, and I myself applied the utmost diligence to that matter, traveling through all of Mesopotamia and Syria, Palestine and Egypt as far as Alexandria, in case I might find it. But I found nothing except some truncated pieces in the city of Damascus. Dschibril himself also found some individual fragments, and others different from mine. Eiub translated those that were extant; for my part, unless the work was complete, I did not want to translate anything, since so few relics remained and the desire for the complete work had seized me. Later, however, I translated into Syriac what was extant; these were portions of the first (?) and second books, the greater part of the third, almost the second half of the fourth, and the ninth book, the beginning of which was missing. I found the remaining later books complete, except that in the final part of book fifteen, something was missing. Isa Ben Iahja translated into Arabic what was extant from book eight and the following books up to the eleventh" (Ishak Ben Honein translated the rest from book eleven onward). I have drawn these Latin translations from the book by Moritz Steinschneider on the life and writings of the Arab philosopher Alfarabius, which is inserted into the Annals of the St. Petersburg Academy, 1869 (Memoirs of the Imperial Academy of Sciences of Saint Petersburg, 7th Series, Vol. XIII, p. 27, note 25).