No conclusion can be formed save on purely logical arguments, and each side advances reasons that carry a certain weight. There is, moreover, at the bottom of the whole discussion, the grave error of identifying the embryonic state of the mind with its adult forms, and of presupposing a sharp initial distinction between discrimination and assimilation. The question must remain open, incapable of positive solution by our psychology. The incontestable truth with regard to the mind, as we know it in its developed and organised state, is that the two processes advance _pari passu_, and are reciprocally causative. In sum, abstraction and generalisation considered as elementary acts of the mind, and reduced to their simplest conditions, involve two processes: 1. The former, _abstraction_, implies a dissociative process, operating on the raw data of experience. It has subjective causes which are ultimately reducible to attention. It has objective causes which may be due to the fact that a determinate quality is given us as an integral part of widely different groups. “Any total impression whose elements are never experienced apart must be unanalysable. If all cold things were wet and all wet things cold, if all liquids were transparent and no non-liquid were transparent, we should scarcely discriminate between coldness and wetness and scarcely ever invent separate names for liquidity and transparency.... What is associated now with one thing and now with another tends to become dissociated from either, and to grow into an object of abstract contemplation by the mind. One might call this the law of dissociation by varying concomitants.”[8] 2. The latter, _generalisation_, originates in association by resemblance, but even in its lowest degree it rises beyond this, since it implies a synthetic act of fusion. It does not, in fact, consist in the successive excitation of similar or analogous percepts, as in the case where the image of St. Peter’s in Rome suggests to me that of St. Paul’s in London, of the Pantheon in Paris, and of other churches with enormous dimensions, of like architecture, and with gigantic domes. It is a condensation. The mind resembles a crucible with a precipitate of common resemblances at the bottom, while the differences have been volatilised. In proportion as we recede from this primitive and elementary form, the constitution of the general idea demands other psychological conditions which cannot be hastily enumerated.