When we compare man's longevity with other forms of life, and consider
that he breathes the same air, drinks the same water, lives under the
same sunshine, and that he differs from them chiefly in his habits of
eating, the conviction is forced upon us that in his food is found the
secret, or the causes of most of his physical ills and his shortened
life. All elements composing the human body are well known. Its daily
needs are matters of common knowledge. Science has separated the human
body into all its various chemical elements or parts, and weighed and
named them; it has also analyzed and separated his food or fuel into
its various chemical elements or parts, and named these. It would seem,
therefore, a most logical step to unite these two branches of science,
and to give to the world the dual science of Physio-food Chemistry, or,
what I have named Applied Food Chemistry.
The sciences of physiological chemistry and of food chemistry can be
made useful only by uniting them--putting them together--fitting one
into the other for the betterment of the human species. These two
branches of science can be of use in no other possible way except
by ascertaining the demands of the human body through physiological
chemistry, and by learning how to supply these demands through the
science of food chemistry. In the union of these hitherto separate
branches of science I can see the most useful, the most important, and
the most powerful department of human knowledge. It is this union that
these volumes are designed to make.