ways, one main object of naming is economy. A single word has to be used to mark a great number of individuals. This will account for such general names as are represented by noun-substantives: man, horse, dog, and so forth. Mill then proceeds, with the help of Horne Tooke, to explain the other grammatical forms. An adjective is another kind of noun marking a cross division. Verbs, again, are adjectives marking other sets of facts, and enabling us to get rid of the necessity of using a new mark for every individual or conceivable combination into clusters. J. S. Mill remarks that this omits the special function of verbs--their 'employment in predication.'[523] James Mill, however, has his own view of 'predication.' 'Man' is a mark of John, Peter, Thomas, and the rest. When I say 'John is a man,' I mean that 'man is another mark to that idea of which John is a mark.'[524] I am then able to make a statement which will apply to all the individuals, and save the trouble of repeating the assertion about each. 'Predication,' therefore, is simply a substitution of one name for another. So, for example, arithmetic is simply naming. What I call two and two, I also call four. The series of thoughts in this case is merely 'a series of names applicable to the same thing and meaning the same thing.'[525] This doctrine, as J. S. Mill remarks, is derived from Hobbes, whom Leibniz in consequence called _plus quam nominalis_.[526] My belief that two and two make four explains why I give the same name to certain numbers; but the giving the name does not explain the belief. Meanwhile, if a class name be simply the mark which is put upon a bundle of things, we have got rid of a puzzle. Mill triumphs over the unfortunate realists who held that a class meant a mysterious entity, existing somewhere apart from all the individuals in which it is embodied. There is really nothing mysterious; a name is first the mark of an individual, the individual corresponding to a 'cluster' or a set of 'simple ideas, concreted into a complex idea.'[527] Then the name and the complex idea are associated reciprocally; each 'calls up' the other. The complex idea is 'associated' with other resembling ideas. The name becomes a talisman calling up the ideas of an indefinite number of resembling individuals, and the name applied to one in the first instance becomes a mark which calls up all, or, as he says, is the 'name of the whole combination.' Classification, therefore, 'is merely a process of naming, and is all resolvable into association.'[528] The peculiarity of this theory, as his commentators again remark, is that it expressly omits any reference to abstraction. The class simply means the aggregate of resembling individuals without any selection of the common attributes which are, in J. S. Mill's phrase, 'connoted' by the class-name. Abstraction, as James Mill explains, is a subsidiary process, corresponding to the 'formation of _sub-species_.'[529]