A powerful, robust, athletic man, in florid health and of temperate habits, yet with the full-blooded tendency of the eighteenth century vividly displayed in his ample face and broad features, Erasmus Darwin bubbled over with irrepressible vivacity, the outward and visible sign of that overflowing energy which forms everywhere one of the most marked determining conditions of high genius. Strong in body and strong in mind, a teetotaler before teetotalism, an abolitionist before the anti-slavery movement, he had a great contempt for weaknesses and prejudices of every sort, and he rose far superior to the age in which he lived in breadth of view and freedom from preconceptions. The eighteenth century considered him, in its cautious, cut-and-dried fashion, a man of singular talent but of remarkably eccentric and unsafe opinions. Unfortunately for his lasting fame, Dr. Darwin was much given to writing poetry; and this poetry, though as ingenious as everything else he did, had a certain false gallop of verse about it which has doomed it to become since Canning's parody a sort of warning beacon against the worst faults of the post-Augustan decadence in the ten-syllabled metre. Nobody now reads the 'Botanic Garden' except either to laugh at its exquisite extravagances, or to wonder at the queer tinsel glitter of its occasional clever rhetorical rhapsodies.
But in his alternative character of philosophic biologist, rejected by the age which swallowed his poetry all applausive, Erasmus Darwin is well worthy of the highest and deepest respect, as a prime founder and early prophet of the evolutionary system. His 'Zoonomia,' 'which, though ingenious, is built upon the most absurd hypothesis'--as men still said only thirty years ago--contains in the germ the whole theory of organic development as understood up to the very moment of the publication of the 'Origin of Species.' In it Dr. Darwin calls attention to 'the great changes introduced into various animals by artificial or accidental cultivation,' a subject afterwards fully elucidated by his greater grandson in his work on 'The Variation of Animals and Plants under Domestication.' He specially notes 'the immense changes of shape and colour' produced by man in rabbits and pigeons, the very species on which Charles Darwin subsequently made some of his most remarkable and interesting observations. More than any previous writer, Erasmus Darwin, with 'prophetic sagacity,' insisted strongly on the essential unity of parent and offspring--a truth which lies at the very base of all modern philosophical biology. 'Owing to the imperfection of language,' wrote the Lichfield doctor nearly a hundred years ago, 'the offspring is termed a new animal, but is in truth a branch or elongation of the parent, since a part of the embryon-animal is or was a part of the parent, and therefore may retain some of the habits of the parent system.' He laid peculiar stress upon the hereditary nature of some acquired properties, such as the muscles of dancers or jugglers, and the diseases incidental to special occupations. Nay, he even anticipated his great descendant in pointing out that varieties are often produced at first as mere 'sports' or accidental variations, as in the case of six-fingered men, five-clawed fowls, or extra-toed cats, and are afterwards handed down by heredity to succeeding generations. Charles Darwin would have added that if these new stray peculiarities happened to prove advantageous to the species they would be naturally favoured in the struggle for existence, while if they proved disadvantageous, or even neutral, they would die out at once or be bred out in the course of a few crosses. That last truth of natural selection was the only cardinal one in the evolutionary system on which Erasmus Darwin did not actually forestall his more famous and greater namesake. For its full perception, the discovery of Malthus had to be collated with the speculations of Buffon.