Our personal identity, then, consists, for Locke, solely in pragmatically definable particulars.  Whether, apart from these verifiable facts, it also inheres in a spiritual principle, is a merely curious speculation.  Locke, compromiser that he was, passively tolerated the belief in a substantial soul behind our consciousness.  But his successor Hume, and most empirical psychologists after him, have denied the soul, save as the name for verifiable cohesions in our inner life.  They redescend into the stream of experience with it, and cash it into so much small-change value in the way of ‘ideas’ and their peculiar connexions with each other.  As I said of Berkeley’s matter, the soul is good or ‘true’ for just so much, but no more.

The mention of material substance naturally suggests the doctrine of ‘materialism,’ but philosophical materialism is not necessarily knit up with belief in ‘matter,’ as a metaphysical principle.  One may deny matter in that sense, as strongly as Berkeley did, one may be a phenomenalist like Huxley, and yet one may still be a materialist in the wider sense, of explaining higher phenomena by lower ones, and leaving the destinies of the world at the mercy of its blinder parts and forces.  It is in this wider sense of the word that materialism is opposed to spiritualism or theism.  The laws of physical nature are what run things, materialism says.  The highest productions of human genius might be ciphered by one who had complete acquaintance with the facts, out of their physiological conditions, regardless whether nature be there only for our minds, as idealists contend, or not.  Our minds in any case would have to record the kind of nature it is, and write it down as operating through blind laws of physics.  This is the complexion of present day materialism, which may better be called naturalism.  Over against it stands ‘theism,’ or what in a wide sense may be termed ‘spiritualism.’  Spiritualism says that mind not only witnesses and records things, but also runs and operates them:  the world being thus guided, not by its lower, but by its higher element.

Treated as it often is, this question becomes little more than a conflict between aesthetic preferences.  Matter is gross, coarse, crass, muddy; spirit is pure, elevated, noble; and since it is more consonant with the dignity of the universe to give the primacy in it to what appears superior, spirit must be affirmed as the ruling principle.  To treat abstract principles as finalities, before which our intellects may come to rest in a state of admiring contemplation, is the great rationalist failing.  Spiritualism, as often held, may be simply a state of admiration for one kind, and of dislike for another kind, of abstraction.  I remember a worthy spiritualist professor who always referred to materialism as the ‘mud-philosophy,’ and deemed it thereby refuted.