1. Introduction. Nowadays metaphysics is so far out of fashion, with scientists at any rate, that a few words of justification may be required for putting it in relation with science, as in this paper.

Metaphysics is nothing occult, nor is it necessarily dogmatic or allied to theology. Strictly, it is a science itself, the science of being. But since a large section of being—even the whole of it, according to some metaphysics—consists of phenomena, and since the ostensible business of natural science is with phenomena, a distinction has to be made. The use of ‘metaphysics’ in this paper is restricted to the non-phenomenal mode of being. More explicitly, it is restricted to formal and general things, such as category, class, variable, relation, order. General words, which I take to be all the words except certain proper names, are, accordingly, metaphysical signs; and the metaphysical matrix is by no means limited to science but extends to all discourse in which there are general terms.