we are more especially enabled to trace those
operations of the earth, by means of the second kind of appearances,
which are now to be mentioned.

These again are the evident changes which those known bodies have
undergone, and which have been induced upon such collected masses of
which those bodies constitute a part. These changes are of three sorts;
_first_, the solid state, and various degrees of it, in which we now
find those masses which had been originally formed by the collection of
loose and incoherent materials; _secondly_, the subsequent changes which
have evidently happened to those consolidated masses which have been
broken and displaced, and which have had other mineral substances
introduced into those broken and disordered parts; and, _lastly_, that
great change of situation which has happened to this compound mass
formed originally at the bottom of the sea, a mass which, after being
consolidated in the mineral region, is now situated in the atmosphere
above the surface of the sea.

In this manner we are led to the system of the world, or theory of the
earth in general; for, that great change of situation, which our land
has undergone, cannot be considered as the work of accident, or any
other than an essential part in the system of this world. It is
therefore a proper view of the necessary connection and mutual
dependence of all those different systems of changing things that forms
the theory of this earth as a world, or as that active part of nature
which the philosophy of this earth has to explore. The animal system is
the first or last of these; next comes the vegetable system, on which
the life of animals depends; then comes the system of this earth,
composed of atmosphere, sea, and land, and comprehending the various
chemical, mechanical, and meteorologically operations which take place
upon that surface where vegetation must proceed; and, lastly, we have
the mineral system to contemplate, a system in which the wasting surface
of the earth is employed in laying the foundation of future land within
the sea, and a system in which the mineral operations are employed in
concocting that future land.

Now, such must surely be the theory of this earth, if the land is
continually wasting in the operations of this world; for, to acknowledge
the perfection of those systems of plants and animals perpetuating their
species, and to suppose the system of this earth on which they must
depend, to be imperfect, an