For the sake of clearness I will take first this last-mentioned form of competition, the process by which one idea drives another out of the intellectual or moral currency of a community. The competition between the idea of fixity of species and Darwin's idea of the unity of life has been already cited as an instance; and it was pointed out that, gradually and after a controversy of some forty years, the former idea almost disappeared, and in the minds at any rate of those who know, the Darwinian theory became victorious. Was it natural selection that brought about the result? To test the matter let us ask once more how natural selection operates. Its mode of operation is always simply negative. And if, in the struggle of life, it selects the courageous man rather than the coward, the temperate man rather than the intemperate, the method by which this result is reached is simple: when it comes to a conflict the courageous man kills the coward or reduces him to subjection; the intemperate man has less vitality than the temperate: he too disappears, although perhaps gradually. Take again the group-competition so far as it is influenced by natural selection. The tribe which manifests the qualities of social solidarity is selected simply in this way, that when it comes into conflict with a tribe which has not this solidarity the latter is beaten, and is thus unable to obtain the pastures or the hunting-ground which it desires, and therefore gradually or swiftly it is exterminated or left behind in the race for life. Now, I ask, Did this process take place when Darwinism supplanted the traditional theory of the fixity of species? Surely it is clear that it is only in the rarest cases that false or inadequate ideas on such subjects have any tendency to shorten life or weaken health. Bishop Wilberforce was killed by a fall from his horse, not by the triumphant dialectic of Professor Huxley. Sir Richard Owen lived to a patriarchal old age, and did not disappear from the face of the earth because he still clung to an idea which the best intellect of his time had relinquished. There is nothing in the doctrine of the fixity of species--if you hold it--which will in the least degree tend to diminish vitality. Natural selection has practically no effect at all in exterminating those who adhere to this idea. There is no means of livelihood from which it would exclude them except indeed that it might prevent them from occupying Chairs of Biology. Apart from that I do not think it will hinder them in any of the various modes of activity in which the struggle for life is manifested.