This continuous changing of the entire human body,--the removal of the
discarded cells, burned up by oxidation and expelled from the body in
the urine, the perspiration and other excretions, and their replacement
by new ones,--is called metabolism, that is, "change of matter."
This change is brought about by means of a vital fluid in the body,
which circulates from the moment in which the spermatozoon, or male
seed, touches the female egg in the womb of the mother, until the time
of our last breath. That fluid is _the blood_,--the carrier of nature's
supplies to all parts of the body for the rebuilding of cells; the exact
and equitable distributor in quantities of material which determines the
quality of the cells.
In its marvelous performance of this function, the blood is the bearer
of the sole existing condition of health; namely the necessary elements
of cell-building in the right proportions.
This is health, and the lack thereof is disease.
The demand of nature for upbuilding and rebuilding is the strongest
instinctive impulse of our being; and this being so, a wrong proportion
may cause the upbuilding of things which are different and disturbing to
the normal organism.
But, on the other hand, kindly nature exhibits an ever existent
inclination to counterbalance any disturbance in the right proportion,
and to bring back conditions to uniformity.
We may thus justly speak of _the overwhelming healing tendency of
nature_.
Metabolism is, therefore, the one great dominant function of the body
which, accordingly, must have our especial care.
It is the blood, consequently, to which alone we can resort if we desire
to assist nature in its process and tendency of balancing and healing.
This again indicates that, notwithstanding the apparent great variety of
_constitutional diseases, they are all practically one and the same
disease. They are all disturbances of proper metabolism, by some
irregularity of the quantitative or qualitative condition of the blood_.
This governing truth the great physiologist, Prof. Jacob Moleschott, has
formulated in the memorable words: "It is one of the chief questions
which humanity must always ask of the physician: how to attain good,
healthy and active blood. And, view the question as we may, all who give
it serious thought, are forced by experience to acknowledge explicitly,
or otherwise, that _our mental and physical capacity, and likewise the
power of reproduction, are directly dependent upon our blood, and our
blood on our nutrition_."