timely savings and accumulations, accomplish what a strong force out of
relation fails to achieve.

We have here a glimpse of the world in which the physical philosopher
for the most part resides. Science has been defined as "organized common
sense;" by whom I have forgotten; but, unless we stretch unduly the
definition of common sense, I think it is hardly applicable to this
world of molecules. I should be inclined to ascribe the creation of that
world to inspiration rather than to what is currently known as common
sense. For the natural history sciences the definition may stand--hardly
for the physical and mathematical sciences.

The sensation of light is produced by a succession of waves which strike
the retina in periodic intervals; and such waves, impinging on the
molecules of bodies, agitate their constituent atoms. These atoms are so
small, and, when grouped to molecules, are so tightly clasped together,
that they are capable of tremors equal in rapidity to those of light and
radiant heat. To a mind coming freshly to these subjects, the numbers
with which scientific men here habitually deal must appear utterly
fantastical; and yet, to minds trained in the logic of science, they
express most sober and certain truth. The constituent atoms of molecules
can vibrate to and fro millions of millions of times in a second. The
waves of light and of radiant heat follow each other at similar rates
through the luminiferous ether. Further, the atoms of different
molecules are held together with varying degrees of tightness--they are
tuned, as it were, to notes of different pitch. Suppose, then,
light-waves, or heat-waves, to impinge upon an assemblage of such
molecules, what may be expected to occur? The same as what occurs when a
piano is opened and sung into. The waves of sound select the strings
which respectively respond to them--the strings, that is to say, whose