Celsus says, that to let blood was no new discovery in his day; but that blood might be let with advantage in almost every disease was a discovery. He states it also as a recent discovery that children, old men, and pregnant women might be safely bled, the operation having been anciently proscribed in all these cases. Yet, notwithstanding the authority of Celsus, the prejudice against bleeding young and old persons seems to have generally prevailed, for it will be perceived, that our author, copying from Galen, forbids persons to be bled before fourteen and after seventy, except in urgent cases. However, Averrhoes mentions that his countryman Avenzoar had bled a child only three years old with great success; and relates further that he had known certain persons who had been bled at the age of eighty. Celsus properly directs us to judge of a patient’s ability to endure venesection from his strength, and not from his tender or advanced age. He also acutely remarks that there is a difference between a strong body and a fat, and between a lean and a weak; for that a lean body contains most blood, and a fat most flesh. (See also Arist. H. A. iii, 19.) Those, therefore, who are lean bear depletion best, and the corpulent suffer most from it. The strength of the body, therefore, is to be estimated from the veins rather than from the general appearance. When the nature of the disease indicates evacuation, and the strength appears ill fitted to bear it, he advises us first to give warning of the danger, and then to abstract blood; for, he adds, “satius est remedium anceps experiri quam nullum.” In general he forbids venesection when the stomach is loaded with impurities; and upon this rule of practice all the ancient authorities, we believe, agree with him. Thus, to give an example from the Arabians, Averrhoes says, our famous physician, Abumeron Avenzoar, states that venesection ought not to be had recourse to until the body is purged, for the veins being emptied of blood attract the crude superfluities. (Collig. vii, 1.) This rule of practice is now too little attended to. In general Celsus holds that the second or third day of a disease is the fittest time for abstracting blood. He forbids bleeding upon the very onset of a fever, which he says is enough to kill a man outright. Upon the whole he approves of letting blood as near as possible to the affected part. He admits, however, that venesection may sometimes act by producing revulsion. The operation, he remarks, although easy to a skilful person may prove dangerous when performed by an unskilful one, as a nerve or artery may be wounded. In securing the arm after the operation he directs us to bind on the wound a compress soaked in cold water. (ii, 10.)