Reflection upon the nature of the evidence by which this conclusion, if supported at all, has to be supported, should convince us that at most all that the statement ought to mean is that individual differences between the elementary constituents of the physical world need not be allowed for in devising practical formulae for the intelligent anticipation of events. When the proposition is put forward as an absolute truth and treated as a reason for denying the ultimate spirituality of the world, we are well within our rights in declining the consequence on the logical ground that conclusions from an empirical premise must in their own nature be themselves empirical and contingent. On the other hand, the extreme empiricism which treats all knowledge whatsoever as merely relative to the total psychical state of the knower, and therefore in the end problematic, must, I apprehend, go down before any serious investigation into the nature of the analytic truths of arithmetic, a consequence which seems to be of some relevance in connection with the philosophic view popularly known as Pragmatism. Thus I should look to the coming regeneration of metaphysics, of which there are so many signs at the moment, on the one hand, for emphatic insistence on the right, _e. g._, of physics and biology and psychology to be treated as purely empirical sciences, and as such freed from the last vestiges of any domination by metaphysical presuppositions and foregone conclusions, and on the other, for an equally salutary purgation of formal studies like logic and arithmetic from the taint of corruption by the irrelevant intrusion of considerations of empirical psychology.