constructions of Nature, and what our experience of Nature warrants us in asserting as the truth regarding a realm external to man’s consciousness. It is with our more modern sciences as it was with early industrial arts. If an industrial art succeeds, that is because Nature actually furnishes us with empirical materials that are plastic for the purposes of this art. We have, however, no right to assert, upon that account, that all natural phenomena, viewed in themselves, and apart from man, already must be so constituted a priori as to be adaptable to the purposes of our human art. The primitive artists who produced the pottery of our American Pueblo Indians, were skilful in finding out just the right sort of clay for their purposes. But had they formed a theory that Nature is in itself essentially a storehouse of good potter’s clay, they would have generalized quite as ill as did primitive Animism when it conceived all Nature as alive in the same sense in which our capricious wills are alive, and are in us subject to our moods and to our senses.
Now, as I have said, our science is a sort of theoretical extension of our industrial art. What the arts do with their tools, the student of science does with his conceptions. That is, he wins over the phenomena of our experience to the service of our human purposes. He does this by processes of selection, of construction, and of an endless process of trial and error. A conception used by any empirical science is an ideal tool, or a sort of mechanical contrivance. Using it, we work over the data of our common experience until these data
