worthy theme. As we follow the evolution of an organism by
studying the stages of its growth, so we have to show how the work
of the scientific investigator is related to the ineffectual
efforts of his predecessors.

In our time we think of the process of development in nature as
one going continuously forward through the combination of the
opposite processes of evolution and dissolution. The tendency of
our thought has been in the direction of banishing cataclysms to
the theological limbo, and viewing Nature as a sleepless plodder,
endowed with infinite patience, waiting through long ages for
results. I do not contest the truth of the principle of continuity
on which this view is based. But it fails to make known to us the
whole truth. The building of a ship from the time that her keel is
laid until she is making her way across the ocean is a slow and
gradual process; yet there is a cataclysmic epoch opening up a new
era in her history. It is the moment when, after lying for months
or years a dead, inert, immovable mass, she is suddenly endowed
with the power of motion, and, as if imbued with life, glides into
the stream, eager to begin the career for which she was designed.

I think it is thus in the development of humanity. Long ages may
pass during which a race, to all external observation, appears to
be making no real progress. Additions may be made to learning, and
the records of history may constantly grow, but there is nothing
in its sphere of thought, or in the features of its life, that can
be called essentially new. Yet, Nature may have been all along
slowly working in a way which evades our scrutiny, until the
result of her operations suddenly appears in a new and
revolutionary movement, carrying the race to a higher plane of