If it be asked what is the right time to let blood, Avicenna44 says, heed not the number of the days, but consider the force of the patient. If it be strong, let a vein on the fifth day, and not only on that day, but on every day thou shalt visit him.45 Nevertheless Avicenna says, if a vein be not opened at the outset of this sickness, there is no use in bleeding him at all, and therefore it is not right to bleed him every time thou visitest him. I reply, in the case of putrid fever that
p.35comes to increase after inception, there is no use46 in bleeding; for he suffers laxatives more readily then than phlebotomy,47 because the matter is digesting: (as) there is no digestion at the beginning of this fever; and therefore a vein may be opened then, if the force, the age and the season permit. Open first the medial vein in the right arm, then the medial vein in the left,48 and thereafter that in the right. Whereupon let the Basilic vein in the right arm, and if needs must the same in the left. If that avail not, let the cupping horn and scarification be applied between his shoulders, and do the same to his calves and both sides of the hips; and let the saphenic vein be opened on both sides in these two cases, as well as the lower vein in the arm on both sides, but first from the right arm, because of the liver, which is the source of the blood.