To the thoughtful mind the outlook at the close of the nineteenth century is profoundly interesting. History can furnish no parallel to it. The problems which loom across the threshold of the new century surpass in magnitude any that civilisation has hitherto had to encounter. We seem to have reached a time in which there is abroad in men's minds an instinctive feeling that a definite stage in the evolution of Western civilisation is drawing to a close, and that we are entering on a new era. Yet one of the most curious features of the time is the almost complete absence of any clear indication from those who speak in the name of science and authority as to the direction in which the path of future progress lies. On every side in those departments of knowledge which deal with social affairs change, transition, and uncertainty are apparent. Despite the great advances which science has made during the past century in almost every other direction, there is, it must be confessed, no science of human society properly so called. What knowledge there is exists in a more or less chaotic state scattered under many heads; and it is not improbably true, however much we may hesitate to acknowledge it, that the generalisations which have recently tended most to foster a conception of the unity underlying the laws operating amid the complex social phenomena of our time, have not been those which have come from the orthodox scientific school. They have rather been those advanced by that school of social revolutionists of which Karl Marx is the most commanding figure.