determining how a system of objects, in which one set of relations (the psychical) is dominant, can interact with a system of the same kind of objects, in which, however, another and an opposite type of relational nexus (the physical) is the primary factor in determining changes. For though the same objects may have simultaneous membership in the psychical and the physical world, yet the ways in which those objects are articulated in the two types of system are strikingly different. Objects, in so far as they are merely members of the physical world, influence each other directly only in virtue of their dynamic or spatio-temporal relations, while their relations of resemblance and difference, and of analogy are only secondarily or indirectly effective. On the other hand, the very same objects, in so far as they are members of a given psychosis, have their changes determined primarily by laws of qualitative similarity and identity of meaning, and only secondarily by spatio-temporal relations. The laws of these two types of system have been to some extent determined, but the relations between them and the conditions under which a psychical system of relations between qualities may, when provided with a suitable protoplasmic matrix, supervene upon the apparantly more permanent physical system of the same qualities, is so far from being determined that there is not as yet any considerable agreement even as to the manner in which the problem should be defined.
This realistic view of the world follows directly and inevitably from Hume's conception of the self as a system of real objects, and not as a system of half-real states or modifications of a subject. The real reasons which led its author to reject it do not, as I have already said, seem to me to lie so much in the arguments which he explicitly gives, and which we have criticized, as in the fact that he was so saturated with the prevailing Lockean and Berkeleyan view of the self as a substance which could have as objects nothing but its own subjective states, that he could not bring himself to see that a series of mental states, which were from moment to moment miraculously created and annihilated, would retain no longer any meaning when there was no longer a substance in which such states could inhere. So it was that the
