The reader will at once perceive the contrast between the spirit of these two passages. In the former Mr. Spencer notes, with great penetration and accuracy, a most important point of difference between two sets of men belonging to the same society. In the latter he deals with societies as single bodies, the members of which possess no personal traits whatever, except such as they all possess alike; and all the traits in which they differ from one another, such as the one just alluded to, of necessity disappear from the field of vision altogether. Should any doubt as to the matter still remain in the reader’s mind, it will be dispelled by {53} the quotation of one further passage. “_A true social aggregate_,” he says [“_as distinct from a mere large family_], _is a union of like individuals, independent of one another in parentage, and approximately equal in capacities_.” Here is the case stated with the most absolute clearness. All congenital inequalities, as was said just now, between the various individuals who make up the aggregate are ignored; and it is upon this hypothesis of approximately equal units, acted on by different external circumstances, that he attempts to build up his whole system of sociology. He is, indeed, little as he himself may suspect it, reproducing in another form the error of Karl Marx and the earlier of the so-called “scientific socialists,” who maintained that all wealth was the product of common or average labour, measured by time, and that hour for hour any one labourer necessarily produced as much wealth as another. The socialists of to-day are already beginning to see that this monstrous, though ingeniously advocated, doctrine is untenable as the foundation of economics; and yet, strange to say, a doctrine strictly equivalent to it forms the accepted foundation of contemporary social science. That science starts with the hypothesis of approximately equal units, and ignores the congenital differences between the individuals who compose the aggregate. We shall find it to be ultimately from differences of this kind that all the practical problems which beset civilisation spring, and that the inability of the modern {54} sociologists, complained of by Mr. Kidd and Professor Marshall, to throw on these problems any definite light is simply the natural and inevitable result of excluding the differences in question altogether from their scientific purview. We will, in the next chapter, consider the whole range of arguments used by Mr. Spencer and others in justification of this error. {55} CHAPTER III GREAT MEN, AS THE TRUE CAUSE OF PROGRESS