nto action. The reading of the works of two men, neither
of them imbued with the spirit of modern science--neither of them,
indeed, friendly to that spirit--has placed me here to-day. These men
are the English Carlyle and the American Emerson. I must ever
gratefully remember that through three long cold German winters
Carlyle placed me in my tub, even when ice was on its surface, at five
o'clock every morning--not slavishly, but cheerfully, meeting each
day's studies with a resolute will, determined whether victor or
vanquished not to shrink from difficulty. I never should have gone
through Analytical Geometry and the Calculus had it not been for those
men. I never should have become a physical investigator, and hence
without them I should not have been here to-day. They told me what I
ought to do in a way that caused me to do it, and all my consequent
intellectual action is to be traced to this purely moral source. To
Carlyle and Emerson I ought to add Fichte, the greatest representative
of pure idealism. These three unscientific men made me a practical
scientific worker. They called out 'Act!' I hearkened to the
summons, taking the liberty, however, of determining for myself the
direction which effort was to take.

And I may now cry 'Act!' but the potency of action must be yours. I
may pull the trigger, but if the gun be not charged there is no
result. We are creators in the intellectual world as little as in the
physical. We may remove obstacles, and render latent capacities
active, but we cannot suddenly change the nature of man. The 'new
birth' itself implies the pre-existence of a character which requires
not to be created but brought forth. You cannot by any amount of
missionary labour suddenly transform the savage into the civilised
Christian. The improvement of man is _secular_--not the work of an hour
or of a day. But though indubitably bound by our organisations, no
man knows what the potentialities of any human mind may be, requiring
only release to be brought into action. There are in the mineral
world certain crystals--certain forms, for instance, of fluor-spar,
which have lain darkly in the earth for ages, but which nevertheless
have a potency of light locked up within them. In their case the
potential has never become actual--the light is in fact held back by a
molecular detent. When these crystals are warmed, the detent is
lifted, and an outflow of light immediately begins. I know n