Man is every instant losing something of himself, and if he was not continually repairing that loss, he would soon necessarily fall into a weakness productive of death. This reparation is effected by aliments. But these aliments must undergo in the body different preparations, which are comprehended under the name of nutrition. But when that nutrition is either not performed, or deficiently so, all these aliments become useless, and do not hinder the falling into all the evils which are the consequence of atrophy or inanition. Of all the causes that may hinder nutrition, there is not perhaps a more common one than over-abundant evacuations. Such is the fabric of our machine, and in general of all human machines, that for aliments to acquire the degree of preparation necessary to repair the body, there must remain in it a certain quantity of humors well elaborated, and, if I may use the expression, naturalised to it. If this condition of them is defective, the digestion and coction of the aliments remains imperfect, and so much the more imperfect, as the humor that is needed requires the most elaboration, and is of the most importance. A healthy robust nurse, from whom the taking some pounds of blood in twenty-four hours, would probably kill, would furnish to her child the same quantity of milk, for four or five days running, without any sensible inconvenience to her, because milk is, of all the humors, that which requires the least elaboration, being, a secretion almost distinct from the humors of the body; whereas blood is an essential of life. There is another humor, the seminal liquid, which has so great an influence over the forces of the body, and over the accomplishment of the digestions which repair them, that the Physicians of all ages have unanimously believed, that the loss of one ounce of this humor weakened more than the loss of forty ounces of blood.