the Invasion or the Reformation).
As long as these comprehensive formulæ remain isolated the conclusion is incomplete. And as it is no longer possible to fuse them into higher generalisations, we feel the need of comparing them for the purpose of classification. This classification may be attempted by two methods.
(1) We may compare together similar categories of special facts, language, religions, arts, governments, taking them from the whole of humanity, and classifying together those which most resemble each other. We obtain families of languages, religions, and governments, which we may again classify and arrange among themselves. This is an abstract kind of classification; it isolates one species of facts from all the others, and thus renounces all claim to exhibit causes. It has the advantage of being rapidly performed and of yielding a technical vocabulary which is useful for designating facts.
(2) We may compare real groups of real individuals, we may take societies which figure in history and classify them according to their similarities. This is a concrete classification analogous to that of zoology, in which, not functions, but whole animals are classified. It is true that the groups are less clearly marked than in zoology; nor is there a general agreement as to the characteristics in respect of which we are to look for resemblances. Are we to choose the economic or the political organisation of the groups, or their intellectual condition? No principle of choice has as yet become obligatory.
History has not yet succeeded in establishing a scientific system of comprehensive classification. Possibly human groups are not sufficiently homogeneous to furnish a solid basis of comparison, and not sharply enough divided to be treated as comparable units.
VIII. The study of