ided in these
matters: they omitted the process of induction, and substituted
conjecture for observation. They could never, therefore, fulfil the
mission of Man to 'replenish the earth, and subdue it.' The
subjugation of Nature is only to be accomplished by the penetration of
her secrets and the patient mastery of her laws. This not only
enables us to protect ourselves from the hostile action of natural
forces, but makes them our slaves. By the study of Physics we have
indeed opened to us treasuries of power of which antiquity never
dreamed. But while we lord it over Matter, we have thereby become
better acquainted with the laws of Mind; for to the mental philosopher
the study of Physics furnishes a screen against which the human spirit
projects its own image, and thus becomes capable of self-inspection.

Thus, then, as a means of intellectual culture, the study of Physics
exercises and sharpens observation: it brings the most exhaustive
logic into play: it compares, abstracts, and generalizes, and provides
a mental scenery appropriate to these processes. The strictest
precision of thought is everywhere enforced, and prudence, foresight,
and sagacity are demanded. By its appeals to experiment, it
continually checks itself, and thus walks on a foundation of facts.
Hence the exercise it invokes does not end in a mere game of
intellectual gymnastics, such as the ancients delighted in, but tends
to the mastery of Nature. This gradual conquest of the external
world, and the consciousness of augmented strength which accompanies
it, render the study of Physics as delightful as it is important.

With regard to the effect on the imagination, certain it is that the
cool results of physical induction furnish conceptions which transcend
the most daring flights of that faculty. Take for example the idea of
an all-pervading aether which transmits a tingle, so to speak, to the
finger ends of the universe every time a street lamp is lighted. The
invisible billows of this aether can be measured with the same ease
and certainty as that with which an engineer measures a base and two
angles, and from these finds the distance across the Thames. Now it
is to be confessed that there may be just as little poetry in the
measurement of an aethereal undulation as in that of the river; for
the intellect, during the acts of measurement and calculation,
destroys those notions of size which appeal to the poetic sense. It
is a mistake to