H.L. Mencken considered Halsted the greatest physician of the whole Johns Hopkins group, and Mencken's praise of his achievements when he reviewed Dr. MacCallum's 1930 biography is a memorable tribute. "His contributions to surgery were numerous and various. He introduced the use of local anesthetics, he was the first to put on rubber gloves, and he devised many new and ingenious operations. But his chief service was rather more general, and hard to describe. It was to bring in a new and better way of regarding the patient. Antisepsis and asepsis, coming in when he was young, had turned the attention of surgeons to external and often extraneous things. Fighting germs, they tended to forget the concrete sick man on the table. Dr. Halsted changed all that. He showed that manhandled tissues, though they could not yell, could yet suffer and die. He studied the natural recuperative powers of the body, and showed how they could be made to help the patient. He stood against reckless slashing, and taught that a surgeon must walk very warily. Dr. William Mayo, one of the cofounders of the Mayo Clinic, once commented that Dr. Halsted took so long to perform procedures that the patients usually healed before he had a chance to close the incision. Though, like most men of his craft, he had no religion, he yet revived and reinforced the ancient saying of Ambroise Paré: 'God cured him; I assisted.' Above all, he was a superb teacher, though he never formally taught. The young men who went out from his operating room were magnificently trained, and are among the great ornaments of American surgery today."