spectator of the events which constitute the history of the
earth. On the first hypothesis, however far back in time that
spectator might be placed, he would see a world essentially,
though perhaps not in all its details, similar to that which now
exists. The animals which existed would be the ancestors of
those which now live, and similar to them; the plants, in like
manner, would be such as we know; and the mountains, plains, and
waters would foreshadow the salient features of our present land
and water. This view was held more or less distinctly, sometimes
combined with the notion of recurrent cycles of change, in
ancient times; and its influence has been felt down to the
present day. It is worthy of remark that it is a hypothesis
which is not inconsistent with the doctrine of
Uniformitarianism, with which geologists are familiar.
That doctrine was held by Hutton, and in his earlier days by
Lyell. Hutton was struck by the demonstration of astronomers
that the perturbations of the planetary bodies, however great
they may be, yet sooner or later right themselves; and that the
solar system possesses a self-adjusting power by which these
aberrations are all brought back to a mean condition.
Hutton imagined that the like might be true of terrestrial
changes; although no one recognised more clearly than he the
fact that the dry land is being constantly washed down by rain
and rivers and deposited in the sea; and that thus, in a longer
or shorter time, the inequalities of the earth's surface must be
levelled, and its high lands brought down to the ocean.
But, taking into account the internal forces of the earth,
which, upheaving the sea-bottom give rise to new land, he
thought that these operations of degradation and elevation might
compensate each other; and that thus, for any assignable time,