from the one of those two things to the other, which seems to
be the data on which he had proceeded in forming his conclusion, is not
sufficient to prove the metamorphosis, even were there not so strong a
physical objection to it; for, it is by no means unusual for mineral
bodies to graduate thus from one substance to another. However that be,
this is not the principal object of the example[42].

[Note 42: Here we have well informed naturalists reasoning with all the
light of our present mineralogy, and maintaining, on the one hand, that
gypsum is transformed into calcedony, by the operation of the meteors,
or some such cause; and, on the other, that a siliceous substance is by
the same means converted into lime-stone. What should we now conclude
from this?--That calcareous and siliceous substances were mutually
convertible. But then this is only in certain districts of Poland and
Siberia. Every where, indeed, we find strange mixtures of calcareous and
siliceous bodies; but neither mineralists nor chemists have, from these
examples, ventured to affirm a metamorphosis, which might have spared
them much difficulty in explaining those appearances.

This is a subject that may be taken in very different lights. In one
view, no doubt, there would appear to be absurdity in the doctrine of
metamorphosis, as there is now a days acknowledged to be in that of
_lusus naturae_; and those reasoning mineralists might thus, in the
opinion of some philosophers, expose their theory to contempt and
ridicule. This is not the light in which I view the subject. I give
those gentlemen credit for diligently observing nature; and I applaud
them for having the merit to reason for themselves, which would seem to
be the case with few of the many naturalists who now speak and write
upon the subject.

Let us now draw an inference, with regard to this, in judging of the
different theories. Either the received system concerning mineral
operations is just, in which case those gentlemen, who employ a secret
metamorphosis, may be to blame in laying it aside; or it is erroneous
and deficient; and, in that case, they have the merit of distinguishing
the error or deficiency of the prevailing system. How far they have seen
the system of nature, in those examples which they have described,
is another question. In the mean time, I am to avail myself of the
testimony of those gentlemen of observation, by which the insufficiency
at least of the received minera