the physicist's matter. It is, for our view, phenomenal, or even epiphenomenal (I owe this latter excellent paradox, I believe, to Professor Stout). It is an object gained by ideal construction and inference, which is of course one aspect of a discovery of the real fact, selected within the universe as accounting for some part of its behaviour. Now just because thus selected, constructed and discriminated by thought, it is itself—say the imperceptible of science—as far removed as possible from anything that could be held to be mental. It has no secondary qualities; and next to none that are primary. I suppose there is no reason to doubt that it represents some actual behaviour within the system of nature; but it is obviously removed as far as possible from the conditions of totality or self-existence, that is, of mind. If you take physical nature as our physical realist took it, and not as the imperceptibles of science, that approaches more nearly to mind, because it is more nearly concrete. But to say that the imperceptibles of science are real, because
