That the abscess is a corruption and transmutation of the flesh or fleshy parts, and what are its modes of formation, and how many kinds of abcesses there are, we have sufficiently explained in the Fourth Book. Now we have only to treat of the operation upon it. If it be completely changed to pus, which we ascertain from the pains, fever (if any was formerly present), redness, pulsation, and the other symptoms of inflammation being diminished, from the swelling assuming a sharp point, and from pus being felt under the fingers upon pressure, more especially if the abscess be superficial, in that case we may proceed to the operation. But if it is not felt to the touch, nor is elevated to a point, owing to its being deep-seated, we must attend to the other symptoms before operating. It is to be understood, however, that before the conversion to pus is completed, we sometimes open abscesses when they are unripe, on account of their being near joints or vital parts, lest, by their continued putrefaction, a ligament or some necessary part should be corrupted by it. And Hippocrates directs us to open abscesses about the anus before they are completely ripened, for fear of their perforating the intestine. In opening them we must not, in all cases, make the incisions in the same manner, but observe the natural lines—as on the face; and the growth of the hairs—as on the head, and taking as much care as possible not to occasion deformity. Straight incisions are to be made in the legs, as in the muscles and tendons; and nerves, arteries, and vital parts are to be avoided, taking care of their safety by sometimes making a straight incision and sometimes a transverse one into the abscess, according to the circumstances of each case. When the abscesses are small we make one incision, but when they are larger we make more, always dividing the thinner parts, and those which are most convenient for the escape of the matter. When the swelling is much raised up to a point, unconcocted, thin, and devoid of vitality, we must cut out a piece either like a triangle, or like a myrtle leaf, or of some other angular figure, because the circular is unfavorable to cicatrization. Those which are not pointed we open by a simple incision, and when we find a sinus, if the part is fleshy and the skin proper for uniting, we only make such incisions into the part as will allow the matter to be discharged; but if it be thin and very devoid of flesh we make a simple incision along its whole length; and after this simple incision, if the parts on each side appear thin and not fleshy we must pare them off. After the operation, having first sponged the part, if the abscess be small, and if only one incision has been made, we may use a simple pledget, but if it be large, and there be many incisions, we draw through them a fillet which can be easily extracted; and when the part has been cut out we fill it in like manner with lint. If a hemorrhage take place