eased
heat of the sun would seriously alter the existing conditions
affecting the evaporation and precipitation of moisture on our
earth; and hence the aqueous forces may also have acted at one
time more powerfully than they do now. The fundamental principle
of catastrophism is, therefore, not wholly vicious; and we have
reason to think that there must have been periods--very remote,
it is true, and perhaps unrecorded in the history of the earth--in
which the known physical forces may have acted with an intensity
much greater than direct observation would lead us to imagine.
And this may be believed, altogether irrespective of those great
secular changes by which hot or cold epochs are produced, and
which can hardly be called "catastrophistic," as they are produced
gradually, and are liable to recur at definite intervals.

Admitting, then, that there _is_ a truth at the bottom of the once
current doctrines of catastrophism, still it remains certain that
the history of the earth has been one of _law_ in all past time,
as it is now. Nor need we shrink back affrighted at the vastness
of the conception--the vaster for its very vagueness--that we
are thus compelled to form as to the duration of _geological
time_. As we grope our way backward through the dark labyrinth
of the ages, epoch succeeds to epoch, and period to period, each
looming more gigantic in its outlines and more shadowy in its
features, as it rises, dimly revealed, from the mist and vapour
of an older and ever-older past. It is useless to add century
to century or millennium to millennium. When we pass a certain
boundary-line, which, after all, is reached very soon, figures
cease to convey to our finite faculties any real notion of the
periods with which we have to deal. The astronomer can employ
material illustrations to give form and substance to our conceptions
of celestial space; but such a resource is unavailable to the
geologist. The few thousand years of which we have historical
evidence sink into absolute insignificance beside the unnumbered
aeons which unroll themselves one by one as we penetrate the dim
recesses of the past, and decipher with feeble vision the ponderous
volumes in which the record of the earth is written. Vainly does
the strained intellect seek to overtake an ever-receding
commencement, and toil to gain some adequate grasp of an apparently
endless succession. A beginning there must have been, though we
can never hope to fix its p