"From a careful consideration of these forms, we ought to draw exactly the same conclusions; firstly, that all are but varieties of one common type; secondly, that it is impossible to consider any of them as the original from which the others have been borrowed; and thirdly, that here again, none of the languages in which these verbal forms occur possess the elements of which they are composed."
All these languages resemble each other so closely that they point to some more ancient language which was to them what Latin was to the six Romance languages; and in the same way we are justified in supposing that all the classes of the vertebrate animals point to the existence of some elder type, now extinct, from which they were all developed.
I have thus stated what are the two hypotheses on this question. There is only one more preliminary which it is needful to notice here, and that is, to caution the reader against the tendency, unhappily too common, of supposing that an adversary holds opinions which are transparently absurd. When we hear an hypothesis which is either novel, or unacceptable to us, we are apt to draw some very ridiculous conclusion from it, and to assume that this conclusion is seriously held by its upholders. Thus the zoologists who maintain the variability of species are sometimes asked if they believe a goose was developed out of an oyster, or a rhinoceros from a mouse? the questioner apparently having no misgiving as to the candour of his ridicule. There are three modes of combating a doctrine. The first is to point out its strongest positions, and then show them to be erroneous or incomplete; but this plan is generally difficult, and sometimes impossible; it is not, therefore, much in vogue. The second is to render the doctrine ridiculous, by pretending that it includes certain extravagant propositions, of which it is entirely innocent. The third is to render the doctrine odious, by forcing on it certain conclusions, which it would repudiate, but which are declared to be "the inevitable consequences" of such a doctrine. Now it is undoubtedly true that men frequently maintain very absurd opinions; but it is neither candid, nor wise, to assume that men who otherwise are certainly not fools, hold opinions the absurdity of which is transparent.
Let us not, therefore, tax the followers of Lamarck, Geoffroy St. Hilaire, or Mr. Darwin with absurdities they have not advocated; but rather endeavour to see what solid argument they have for the basis of their hypothesis.
