iple of
the invariability of the laws of Nature, insisted that affairs had
always gone on at the same rate and in the same way as they do now.
Hence it maintained an opposition to the catastrophists, and in this, it
may be said, was actually not true to its own principles. Any doctrine
of uniformity, rightly considered from its most general point of view,
includes an admission of catastrophes. Numerous illustrations of this
truth spontaneously suggest themselves. A tower, the foundations of
which are slowly yielding, may incline more and more for many centuries,
but the day must come in which it will fall at last. In the uniformity
of the disturbance a catastrophe was eventually involved. And thus, in
what has been said respecting geological events, though they are spoken
of as proceeding quietly and with uniformity, it may be understood that
sudden crises are also contemplated. Moreover, those who adopt the
doctrine of uniformity in an absolute sense must pay a due regard to the
variations in intensity of physical acts which their own principles
imply. The uniform cooling of a hot body actually means a cooling at
first fast, and then slower and slower; and invariability of chemical
change actually implies more violent and summary modifications at a high
temperature than at one which is low.

But, though it may at first sight have appeared that an admission of the
doctrine of catastrophes is in harmony with a providential government of
the world, and that the emergence of different organic forms in
successive ages is a manifestation of creative intervention, of which it
was admitted that as many as from twelve to twenty, if no more,
successive instances might be recognized, we may well congratulate
ourselves that those important doctrines rest upon a far more
substantial basis. Rightly considered, the facts lead to a very
different conclusion. [Sidenote: Successive forms assumed by man.]
Physiological investigations have proved that all animals, even man,
during the process of development, pass in succession through a definite
cycle of forms. Starting from a simple cell, form after form, in a
definite order is assumed. In this long line of advance the steps are
ever, in all individuals, the same. But no one would surely suppose that
the changed aspect at any moment presented is due to a providential
interposition. [Sidenote: But they are rigidly determined by law.] On
the contrary, it is the inevitable result of what ha