I like our looking a “way” which is “practically unthinkable” “clearly in the face.” I particularly like “practically unthinkable.” I suppose we can think it in theory, but not in practice. I like almost everything Mr. Allen says or does; it is not necessary to go far in search of his good things; dredge up any bit of mud from him at random and we are pretty sure to find an oyster with a pearl in it, if we look it clearly in the face; I mean, there is sure to be something which will be at any rate “almost” practically unthinkable. But however this may be, when Mr. Allen wrote his article in “Mind” two years ago, he was in substantial agreement with myself about the value of natural selection as a means of modification—by natural selection I mean, of course, the commonly known Charles-Darwinian natural selection from fortuitous variations; now, however, in 1885, he is all for this same natural selection again, and in the preface to his “Charles Darwin” writes (after a handsome acknowledgment of “Evolution Old and New”) that he “differs from” me “fundamentally in” my “estimate of the worth of Charles Darwin’s distinctive discovery of natural selection.” This he certainly does, for on page 81 of the work itself he speaks of “the distinctive notion of natural selection” as having, “like all true and fruitful ideas, more than once flashed,” &c. I have explained _usque ad nauseam_, and will henceforth explain no longer, that natural selection is no “distinctive notion” of Mr. Darwin’s. Mr. Darwin’s “distinctive notion” is natural selection from among fortuitous variations. Writing again (p. 89) of Mr. Spencer’s essay in the “Leader,” {218a} Mr. Allen says:— “It contains, in a very philosophical and abstract form, the theory of ‘descent with modification’ without the distinctive Darwinian adjunct of ‘natural selection’ or survival of the fittest. Yet it was just that lever dexterously applied, and carefully weighted with the whole weight of his endlessly accumulated inductive instances, that finally enabled our modern Archimedes to move the world.” Again:— “To account for adaptation, for the almost perfect fitness of every plant and every animal to its position in life, for the existence (in other words) of definitely correlated parts and organs, we must call in the aid of survival of the fittest. Without that potent selective agent, our conception of the becoming of life is a mere chaos; order and organisation are utterly inexplicable save by the brilliant illuminating ray of the Darwinian principle” (p. 93). And yet two years previously this same principle, after having been thinkable for many years, had become “unthinkable.”