The ORIGIN OF SPECIES led to the THIRD stage of the fortunes of the idea of Progress. We saw how the heliocentric astronomy, by dethroning man from his privileged position in the universe of space and throwing him back on his own efforts, had helped that idea to compete with the idea of a busy Providence. He now suffers a new degradation within the compass of his own planet. Evolution, shearing him of his glory as a rational being specially created to be the lord of the earth, traces a humble pedigree for him. And this second degradation was the decisive fact which has established the reign of the idea of Progress. 2. Evolution itself, it must be remembered, does not necessarily mean, applied to society, the movement of man to a desirable goal. It is a neutral, scientific conception, compatible either with optimism or with pessimism. According to different estimates it may appear to be a cruel sentence or a guarantee of steady amelioration. And it has been actually interpreted in both ways. In order to base Progress on Evolution two distinct arguments are required. If it could be shown that social life obeys the same general laws of evolution as nature, and also that the process involves an increase of happiness, then Progress would be as valid a hypothesis as the evolution of living forms. Darwin had concluded his treatise with these words: As all the living forms of life are the lineal descendants of those which lived long before the Silurian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence we may look with some confidence to a secure future of equally inappreciable length. And as natural selection works solely by and for the good of each being, all corporeal and mental environments will tend to progress towards perfection. Here the evolutionist struck the note of optimism. And he suggested that laws of Progress would be found in other quarters than those where they had hitherto been sought. The ablest and most influential development of the argument from evolution to Progress was the work of Spencer. He extended the principle of evolution to sociology and ethics, and was the most conspicuous interpreter of it in an optimistic sense. He had been an evolutionist long before Darwin's decisive intervention, and in 1851 he had published his Social Statics, which, although he had not yet worked out the evolutionary laws which he began to formulate soon afterwards and was still a theist, exhibits the general trend of his optimistic philosophy. Progress here appears as the basis of a theory of ethics. The title indicates the influence of Comte, but the argument is sharply opposed to the spirit of Comte's teaching, and sociology is treated in a new way. [Footnote: Social Statics, or the Conditions Essential to Human Happiness specified, and the first of them developed, is the full title.]