On the Surgery

Part 1

It's the business of the physician to know, in the first place, things similar and things dissimilar; those connected with things most important, most easily known, and in anywise known;

The meaning of the first clause of this sentence, according to Galen, is, that the first thing which the medical practitioner must do is to make himself well acquainted with semeiology, by comparing carefully the condition of disease with that of health. In all cases of accident, it was the practice of the ancient surgeons to compare carefully the injured part with its fellow or corresponding part on the opposite side.

which are to be seen, touched, and heard; which are to be perceived in the sight, and the touch, and the hearing, and the nose, and the tongue, and the understanding; which are to be known by all the means we know other things.

Part 2

The things relating to surgery, are- the patient; the operator; the assistants; the instruments; the light, where and how; how many things, and how; where the body, and the instruments; the time; the manner; the place.

Part 3

The operator is either sitting or standing, conveniently for himself, for the person operated upon, for the light. There are two kinds of light, the common and the artificial; the common is not at our disposal, the artificial is at our disposal. There are two modes of using each, either to the light, or from the light (to the side?). There is little use of that which is from (or oblique to the light), and the degree of it is obvious. As to opposite the light, we must turn the part to be operated upon to that which is most brilliant of present and convenient lights, unless those parts which should be concealed, and which it is a shame to look upon; thus the part that is operated upon should be opposite the light, and the operator opposite the part operated