It gets warm when it runs, and stops if it is not fed.
[Illustration: TO ATTEMPT TO RUN AN AUTOMOBILE WITHOUT KNOWING HOW WOULD BE REGARDED AS FOOLHARDY] There is not an unnecessary part, or unreasonable "cog," anywhere in the whole of our bodies.

It is true that there are a few little remnants which are not quite so useful as they once were, and which sometimes cause trouble.

But for the most part, all we have to do is to look long and carefully enough at any organ or part of our bodies, to be able to puzzle out just what it is or was intended to do, and why it has the shape and size it has.
Why the Study of Physiology is Easy.

There is one thing that helps to make the study of physiology quite easy.

It is that you already know a good deal about your body, because you have had to live with it for a number of years past, and you can hardly have helped becoming somewhat acquainted with it during this time.
You have, also, another advantage, which will help you in this study.
While your ideas of how to take care of your body are rather vague, and some of them wrong, most of them are in the main right, or at least lead you in the right direction.