of how to kindle a fire, could
make use of a steam-engine." The natural rate of flow of this energy
from its atomic sources we get as heat, and it suffices to keep life
going upon this planet. It is the source of all the activity we see upon
the globe. Its results, in the geologic ages, are stored up for us in
coal and oil and natural gas, and, in our day, are available in the
winds, the tides, and the waterfalls, and in electricity.

IV

The electric constitution of matter is quite beyond anything we can
imagine. The atoms are little worlds by themselves, and the whole
mystery of life and death is in their keeping. The whole difference in
the types of mind and character among men is supposed to be in their
keeping. The different qualities and properties of bodies are in their
keeping. Whether an object is hot or cold to our senses, depends upon
the character of their vibrations; whether it be sweet or sour,
poisonous or innocuous to us, depends upon how the atoms select their
partners in the whirl and dance of their activities. The hardness and
brilliancy of the diamond is supposed to depend upon how the atoms of
carbon unite and join hands.

I have heard the view expressed that all matter, as such, is dead
matter, that the molecules of hydrogen, oxygen, carbon, nitrogen, iron,
phosphorus, calcium, and so on, in a living body, are themselves no more
alive than the same molecules in inorganic matter. Nearly nine tenths of
a living body is water; is not this water the same as the water we get
at the spring or the brook? is it any more alive? does water undergo any
chemical change in the body? is it anything more than a solvent, than a
current that carries the other elements to all parts of the body? There
are any number of chemical changes or reactions in a living body, but
are the atoms and molecules that are involved in such changes radically
changed? Can oxygen be anything but oxygen, or carbon anything but
carbon? Is what we call life the result of their various new
combinations? Many modern biologists hold to this view. In this
conception merely a change in the order of arrangement of the molecules
of a substance--which follows which or which is joined to which--is
fraught with consequences as great as the order in which the letters of
the alphabet are arranged in words, or the words themselves are arranged
in sentences. The change of one letter in a word often utterly changes
the meaning of that word, and the