fusion may be produced, must be an
occult cause, one which cannot be admitted into natural philosophy.

By thus choosing to consider mountains as of two distinct kinds, one
aquiform which is understood, and the other primordial which is not to
be known, we supersede the necessity of reconciling a theory with many
appearances in nature which otherwise might be extremely inconvenient
to our explanation, if not inconsistent with our system. Our author no
doubt has thus relieved himself from a considerable difficulty in the
philosophy of this earth, by saying here is a great part which is not
to be explained. But I would beg leave to observe, that this form of
discussion, with regard to a physical subject, is but a mere confession
of our ignorance, and has no tendency to clear up another part of the
subject of which one treats, however it may impress us with a favourable
opinion of the theorist, in allowing him all the candour of the
acknowledgement.

The general result of the reasoning which we now have quoted, and what
follows in his examination, seems to terminate in this; that there are
various different compositions of mountains which this author cannot
allow to be the production of the sea; but it is not upon account of
the matter of which they are formed, or of the particular mixture and
composition of those species of matter, of which the variety is almost
indefinite. According to this philosopher, the distinction that we are
to make of those primordial and secondary competitions, consists in
this, that the first are in such a shape and structure as cannot be
conceived to be formed by subsidence in water.

M. de Saussure has carefully examined those same objects; and he seems
inclined to think that they must have been the operation of the ocean;
not in the common manner of depositing strata, but in some other way by
crystallization. The present theory supposes all those masses formed
originally in the ordinary manner, by the deposits or subsidence
of materials transported in the waters, and that those strata were
afterwards changed by operations proper to the mineral regions.

But the subject of the present investigation goes farther, by inquiring
if, in the operations of the globe, a primary and secondary class of
bodies may be distinguished, so far as the one may have undergone the
operations of the globe, or the vicissitudes of sea and land, oftener
than the other, consequently must be anterior to the later pr