masses of melted substances, by the operation of
mineral causes. But, though all those things be similar, or equal, as to
the manner of their production, they are far from being so with regard
to the periods of their original composition, or to the subsequent
operations which they may have undergone.

There is a certain order established for the progress of nature, for the
succession of things, and for the circulation of matter upon the surface
of this globe; and, the order of time is associated with this change of
things. But it is not in equal portions that time is thus combined with
dissimilar things, nor always found, in our estimation, as equally
accompanying those which we reckon similar. The succession of light and
darkness is that which, in those operations, appears to us most steady;
the alternation of heat and cold comes next, but not with equal
regularity in its periods. The succession of wet and dry upon the
surface of the earth, though equally the work of nature and the effect
of regular causes, is often to us irregular, when we look for equal
periods in the course of things which are unequal. It is by equalities
that we find order in things, and we wish to find order every where.

The present object of our contemplation is the alternation of land
and water upon the surface of this globe. It is only in knowing this
succession of things, that natural appearances can be explained; and
it is only from the examination of those appearances, that any certain
knowledge of this operation is to be obtained. But how shall we acquire
the knowledge of a system calculated for millions, not of years only,
nor of the ages of man, but of the races of men, and the successions of
empires? There is no question here with regard to the memory of man, of
any human record, which continues the memory of man from age to age; we
must read the transactions of time past, in the present state of natural
bodies; and, for the reading of this character, we have nothing but
the laws of nature, established in the science of man by his inductive
reasoning.

It has been in reasoning after this manner, that I have endeavoured to
prove, that every thing which we now behold, of the solid parts of this
earth, had been formerly at the bottom of the sea; and that there is, in
the constitution of this globe, a power for interchanging sea and land.
If this shall be admitted as a just view of the system of this globe,
we may next examine, how far t