out of the sea, was never tenanted by a living oyster, but is a
mineral concretion, there is no demonstrating his error.
All that can be done is to show him that, by a parity of
reasoning, he is bound to admit that a heap of oyster shells
outside a fishmonger's door may also be "sports of nature," and
that a mutton bone in a dust-bin may have had the like origin.
And when you cannot prove that people are wrong, but only that
they are absurd, the best course is to let them alone.

The whole fabric of palaeontology, in fact, falls to the ground
unless we admit the validity of Zadig's great principle, that
like effects imply like causes, and that the process of
reasoning from a shell, or a tooth, or a bone, to the nature of
the animal to which it belonged, rests absolutely on the
assumption that the likeness of this shell, or tooth, or bone,
to that of some animal with which we are already acquainted, is
such that we are justified in inferring a corresponding degree
of likeness in the rest of the two organisms. It is on this very
simple principle, and not upon imaginary laws of
physiological correlation, about which, in most cases, we know
nothing whatever, that the so-called restorations of the
palaeontologist are based.

Abundant illustrations of this truth will occur to every one who
is familiar with palaeontology; none is more suitable than the
case of the so-called Belemnites. In the early days of
the study of fossils, this name was given to certain elongated
stony bodies, ending at one extremity in a conical point, and
truncated at the other, which were commonly reputed to be
thunderbolts, and as such to have descended from the sky.