ears. With heat enough the earth would melt like a
snowball in a furnace, with still more it would become a vapor and float
away like a cloud. More or less heat only makes the difference between
the fluidity of water and the solidity of the rocks that it beats
against, or of the banks that hold it.

The physical history of the universe is written in terms of heat and
motion. Astronomy is the story of cooling suns and worlds. At a low
enough temperature all chemical activity ceases. In our own experience
we find that frost will blister like flame. In the one case heat passes
into the tissues so quickly and in such quantity that a blister ensues;
in the other, heat is abstracted so quickly and in such quantity that a
like effect is produced. In one sense, life is a thermal phenomenon; so
are all conditions of fluids and solids thermal phenomena.

Great wonders Nature seems to achieve by varying the arrangement of the
same particles. Arrange or unite the atoms of carbon in one way and you
have charcoal; assemble the same atoms in another order, and you have
the diamond. The difference between the pearl and the oyster-shell that
holds it is one of structure or arrangement of the same particles of
matter. Arrange the atoms of silica in one way and you have a quartz
pebble, in another way and you have a precious stone. The chemical
constituents of alcohol and ether are the same; the difference in their
qualities and properties arises from the way the elements are
compounded--the way they take hold of hands, so to speak, in that
marriage ceremony which constitutes a chemical compound. Compounds
identical in composition and in molecular formulae may yet differ widely
in physical properties; the elements are probably grouped in different
ways, the atoms of carbon or of hydrogen probably carry different
amounts of potential energy, so that the order in which they stand
related to one another accounts for the different properties of the same
chemical compounds. Different groupings of the same atoms of any of the
elements result in a like difference of physical properties.

The physicists tell us that what we call the qualities of things, and
their structure and composition, are but the expressions of internal
atomic movements. A complex substance simply means a whirl, an intricate
dance, of which chemical composition, histological structure, and gross
configuration are the figures. How the atoms take hold of hands, as it
were, t