of this world, which may be considered as a species
of organised body. Here, therefore, final causes are to be brought into
view, as well as those which are efficient. Now, in a subject involved
with so much obscurity, as must be for us the internal regions of the
globe, the consideration of efficient and final causes may contribute
mutually to each others evidence, when separately the investigation of
either might be thought unsatisfactory or insufficient.

So far it seemed necessary to premise with regard to the great mineral
power which we are to employ as an agent in the system of this earth;
and it may be now observed, that it is in the proper relation of this
power of heat and the fluidity or softness of bodies, as cause and
effect, that we are to find a physical principle or argument for
detecting those false theories of the earth that have been only
imagined, and not properly founded on fact or observation. It is also by
means of this principle, that we shall be enabled to form a true theory
of the mineral region, in generalising particular effects to a common
cause.

Let us now proceed in endeavouring to decide this important question,
viz. By what active principle is it, that the present state of things,
which we observe in the strata of the earth, a state so very different
from that in which those bodies had been formed originally, has been
brought about?

Two causes have been now proposed for the consolidating of loose
materials which had been in an incoherent state; these are, on the one
hand, fire; or, on the other, water, as the means of bringing about that
event. We are, therefore, to consider well, what may be the consequences
of consolidation by the one or other of those agents; and what may be
the respective powers of those agents with respect to this operation.

If we are not informed in this branch of science, we may gaze without
instruction upon the most convincing proofs of what we want to attain.
If our knowledge is imperfect, we may form erroneous principles, and
deceive ourselves in reasoning with regard to those works of nature,
which are wisely calculated for our instruction.

The strata, formed at the bottom of the sea, are to be considered
as having been consolidated, either by aqueous solution and
crystallization, or by the effect of heat and fusion. If it is in the
first of these two ways that the solid strata of the globe have attained
to their present state, there will be a certain