[Sidenote: Food chemistry useless without body chemistry]
Until my work began these two great sciences had been taught as distinct
and separate branches of learning, while in reality _physiological
chemistry_ is but half of a science, and _food chemistry_ is, in fact,
the other half of the same science. The energy in food cannot be
developed without the body--the body cannot develop energy without food.
Each branch is worthless, therefore, without the other. In this work
I have endeavored to unite them and to make of the two one practical,
provable, and usable science.