A Byzantine anatomical and physiological treatise almost entirely abridged from Galen's "De usu partium corporis humani," from which Theophilus now and then differed, and which he sometimes appears to have misunderstood. "In the fifth book he has inserted large extracts from Hippocrates' 'De Genitura,' and 'De Natura Pueri."'He recommends in several places the dissection of animals, but he does not appear ever to have examined a human body: in one passage he advises the student to dissect an ape, or else a bear, or, if neither of these animals can be procured, to take whatever he can get, 'but by all means,' he adds, 'let him dissect something' " (Wikipedia article on Theophilus Protospatharius). This is apparently the only surviving medical treatise by Theophilus. Digital facsimile from Google Books at this link.