Professor Jacob Moleschott, the great physiologist, has crystallized
this truth in the immortal words: "One of the principal questions to be
always asked of the physician is this: How may good healthy and active
blood be obtained? View the question as we may, we shall be forced to
acknowledge openly and explicitly or guardedly and indirectly that our
volition, our sensations, our strength, and our pro-creative powers are
dependent upon our blood and our blood upon our nutrition."

If such unity exists, why then the great difference in the human organs?
How is it that a bone in its stonelike hardness is essentially the same
as the exquisitely sensitive eye?

This is owing to the adaptive property of the cells, in the course of
their enormous accumulation, to different functions, which, again,
depends upon the varied arrangement of the constituent elements. These
elements all find lodgement in the blood, and are carried by it in
necessary quantities to the points where they are needed to assist the
organs in replacing consumed matter.

The difficulty found in grasping this idea of _unity_ has led to the
most momentous errors in modern medical science.

One result has been the undue attention paid to the study of anatomy,
insomuch that the different organs are regarded as wholly distinct
groups of cells. This is convenient from a descriptive standpoint, but
it tends too much to draw attention away from the source of life, and of
health. Only by noting the common characteristics of the cell
accumulations termed organs, are we enabled to supply the necessary
elements that may be lacking. And thus we arrive at the subject of _the
chemical analysis of the human body_ and its various organs, a subject