It was speedily seen, however, that such generalizations were so broad and vague as not to be of much service: that the resemblances were in fact often no more than symbolical or metaphorical, instead of being based upon detailed similarity of constitution or of evolutionary development. With this, evolutionary theorizing on sociological matters fell somewhat into disrepute. The earlier jubilant certainty gave place to later doubt; and the half-century whose beginnings had roused Haeckel and Herbert Spencer to their imaginative flights closed suitably enough with that remarkable document, T. H. Huxley’s Romanes Lecture, in which the greatest protagonist of Darwinism confesses to seeing between man and the rest of the cosmic process, in spite of man’s genesis from that same cosmic process, an insuperable and essential opposition, a difference of aim or direction which had turned the original bridge into a barrier.[18] As a result, not only did the particular comparison between society and an organism fall into disrepute, but also all attempts to draw far-reaching conclusions from biology to human affairs. But the original contention still remains, and is logically unassailable. Man is an organism descended from lower organisms; his communities are composed of units bound together for mutual good in a division of labour in the same way as are the cells of a metazoan: he can no more escape the effects of his terrestrial environment than can other organisms. There _is_ therefore reason to suppose that the processes of evolution in man and man’s societies on the one hand, and in lower organisms on the other, must have something important and indeed fundamental in common, something which if we could but unravel would help us in the study of both. The correlation of biology with sociology is important not only in itself, but also as part of a more general correlation of all the sciences. The correlation of the sciences is of particular importance to-day for a double set of reasons. The rise of evolutionary biology and of modern psychology have not only changed our outlook on specially human problems, but have altered the whole balance, if I may so put it, of science. There was a time when the basic studies of physics and chemistry seemed not only basic but somehow more essentially scientific than the sciences dealing with life. Distinctions were drawn between the experimental and the observational sciences--often half-consciously implying a distinction between accurate, scientific, self-respecting sciences and blundering, hit-or-miss, tolerated bodies of knowledge. Biological phenomena are now, however, seen to be every whit as susceptible of accurate and experimental analysis; and indeed to present so many problems to the physicist and chemist that in fifty years or so, I venture to prophesy, the wise virgins in those basic sciences will be those who have laid in a store of biological oil.