It is still a secret lying hidden within the human body, that whatever any internal organ or part of an organ, even the smallest part, requires for its nourishment and thus conservation, it gets from the whole body. It gets [what it needs] both in the fluids, that is, the blood stream, and in the non-fluids, which must jointly come to its aid, from near and far. Thus the whole exists for the least parts, wherever they may be in the body; and the least parts do not regard anything as their own, but for the common cause when some other part requires it for that use. This is a secret in the animate body, but it comes to light in innumerable things, and it can be demonstrated, because it is true.