ld that he failed
to see the consequences of his own premises. No one could have seen more
clearly, nor have said more lucidly, what should suffice to show a
sympathetic reader the conclusion he ought to come to. Even when
ironical, his irony is not the ill-natured irony of one who is merely
amusing himself at other people's expense, but the serious and legitimate
irony of one who must either limit the circle of those to whom he
appeals, or must know how to make the same language appeal differently to
the different capacities of his readers, and who trusts to the good sense
of the discerning to understand the difficulty of his position and make
due allowance for it.

The compromise which he thought fit to put before the public was that
"Each species has a type of which the principal features are engraved in
indelible and eternally permanent characters, while all accessory touches
vary." {177a} It would be satisfactory to know where an accessory touch
is supposed to begin and end.

And again:--

"The essential characteristics of every animal have been conserved
without alteration in their most important parts. . . . The
individuals of each genus still represent the same forms as they did
in the earliest ages, especially in the case of the larger animals"
(so that the generic forms even of the larger animals prove not to be
the same, but only "especially" the same as in the earliest ages).
{177b}

This transparently illogical position is maintained ostensibly from first
to last, much in the same spirit as in the two foregoing passages,
written at intervals of thirteen years. But they are to be read by the
light of the earlier one--placed as a lantern to the wary upon the
threshold of his work in 1753--to the effect that a single,
well-substantiated case of degeneration would make it conceivable that
all living beings were descended from but one common ancestor. If after
having led up to this by a remorseless logic, a man is found five-and-
twenty years later still substantiating cases of degeneration, as he has
been substantiating them unceasingly in thirty quartos during the whole
interval, there should be little question how seriously we are to take
him when he wishes us to stop short of the conclusions he has told us we
ought to draw from the premises that he has made it the business of his
life to establish--especially when we know that he has a Sorbonne to keep
a sharp eye upon him.