This manuscript contains the four books on surgery (Chirurgia) by the Dominican friar Teodorico Borgognoni of Lucca. He advocated the use of antiseptic surgery at a time when it was believed that pus was a beneficial sign of healing (supposedly for facilitating the elimination of unhealthy humors from the wounded body). He criticized the practice of using unguents and poultices to generate pus in a wound. Truly, he described his innovative surgical techniques in detail, including procedures for cleaning the wound, eliminating dead tissue, and closing the walls of the wound by using stitches.