15th Century dissection. Historical print of a dissection in progress at a medical school during the 15th Century. At centre a demonstrator dissects the corpse to illustrate anatomy. At top left a professor, for whom it was considered too demeaning to actually do the cutting, reads aloud from a medical book. Medieval medical books were commonly derived from the ancient works of Roman writers, particularly the physician and anatomist Galen (130-200). Galen's work had been mainly done on animals, with the results (sometimes incorrectly) applied to human anatomy. These errors were compounded by mistakes in copying and translation.