It is true that, if we use the word science in a certain sense, the attempt to treat social problems scientifically is not in itself new. Political economy, to say nothing of utilitarian ethics, is a social science, or it is nothing; and political economy had already made considerable advances when modern physical science had hardly found its footing. But before long physical science passed it, with a step that was not only more rapid, but also immeasurably firmer, and was presently giving such an example of what {6} accurate science is, that it was thought doubtful whether political economy could be called a science at all. The doubt thus raised cannot be said to have justified itself. In spite of all the attacks that have been made against the earlier economists, their principal doctrines survive to the present day, as being, so far as they go, genuine scientific truths. But whenever the thinker, who has been educated in the school of modern physical science, betakes himself now to the study of society and human action, and begins to apply to these the developed theory of evolution, though he does not reject the doctrines of the earlier economists, he sees them in a new light, by which their significance is profoundly changed. The earlier economists took society as they found it, and they reasoned as though what was true of the economic life around them must be absolutely and universally true of economic life always. Here is the point as to which the thinker of to-day differs from them. He does not dispute the truth of the deductions drawn by them with regard to society as it existed during their own epoch; but, educated by the methods and discoveries of the physical and biological evolutionist, he perceives that society itself is in process of constant change, that many economic doctrines which have been true during the present century had little application to society during the Middle Ages, and that centuries hence they may perhaps have even less. Thus, though he does not repudiate or disregard the economic science of the past, he {7} merges it in a science the scope of which is far wider and deeper. This is a science which primarily sets itself to explain, not how a given set of social conditions affects those who live among them, but how social conditions at one epoch are different from those of another, how each set of conditions is the resultant of those preceding it, and how, since the society of the present differs from that of the past, the society of the future is likely to differ from that of the present.