While Mondeville is devoted to the principle that authority is of great value, he said that there was nothing perfect in things human, and successive generations of younger men often made important additions to what their ancestors had left them. While his work is largely a compilation, nearly everywhere it shows signs of the modification of his predecessors' opinions by the results of his own experience. His method of writing is, as Pagel declares, "always interesting, lively, and often full of meat." He had a teacher's instinct, for in several of the earlier manuscripts his special teaching is put in larger letters in order to attract students' attention.... He seems to have introduced or re-introduced into practice the idea of the use of a large magnet in order to extract portions of iron from the tissues. He made several modifications in needles and thread holders and invented a kind of small derrick for the extraction of arrows with barbs. Besides, he suggested the surrounding of the barbs of the arrows with tubes, to facilitate extraction. In his treatment of wounds, Pagel considers that as a writer and teacher he is far ahead of his predecessors and even of those who came after him in immediately subsequent generations. One of his great merits undoubtedly is that Guy de Chauliac, the father of modern surgery, in his text-book turned to him with a confidence that proclaims his admiration and how much he felt that he had gained from him. One of the most interesting features of Mondeville's work is his insistence on the influence of the mind on the body and the importance of using this influence to the best advantage. It is especially important in Mondeville's opinion to keep a surgical patient from being moody. "Let the surgeon," says he, "take care to regulate the whole regimen of the patient's life for joy and happiness by promising that he will soon be well, by allowing his relatives and special friends to cheer him and by having someone to tell him jokes, and let him be solaced also by music on the viol or psaltery. The surgeon must forbid anger, hatred, and sadness in the patient, and remind him that the body grows fat from joy and thin from sadness. He must insist on the patient obeying him faithfully in all things." He repeats with approval the expression of Avicenna that "often the confidence of the patient in his physician does more for the cure of his disease than the physician with all his remedies." Obstinate and conceited patients prone to object to nearly everything that the surgeon wants to do, and who often seem to think that they surpass Galen and Hippocrates in science and wisdom, are likely to delay their cure very much, and they represent the cases with which the surgeon has much difficulty.