(_d_) A very widespread notion of substance is the conception of it as a “_permanent_,” “_stable_,” “_persisting_” subject of “_transient_,” “_ephemeral_” realities called accidents or phenomena. This view of substance is mainly due to the influence of Kant’s philosophy. According to his teaching we can think the succession of phenomena which appear to our sense consciousness only by the aid of a pure intuition in which our sensibility apprehends them, _viz._ _time_. Now the application of the category of substance to this pure intuition of our sensibility engenders a _schema_ of the imagination, _viz._ the _persistence_ of the object in time. Persistence, therefore, is for him the essential note of substance. Herbert Spencer, too, has given apt expression to this widely prevalent notion: “Existence means nothing more than persistence; and hence in Mind that which persists in spite of all changes, and maintains the unity of the aggregate in defiance of all attempts to divide it, is that of which existence in the full sense of the word must be predicated—that which we must postulate as the substance of Mind in contradistinction to the varying forms it assumes. But if so, the impossibility of knowing the substance of Mind is manifest.”(244) Thus, substance is conceived as the unique but hidden and unknowable basis of all the phenomena which constitute the totality of human experience. What is to be said of such a conception? There is just this much truth in it: that substance is _relatively_ stable or permanent, _i.e._ in comparison with accidents; the latter cannot survive the destruction or disappearance of the substance in which they inhere, while a substance can persist through incessant change of its accidents. But accidents are not _absolutely_ ephemeral, nor is substance _absolutely_ permanent: were an accident to exist for ever it would not cease to be an accident, nor would a substance be any less a substance were it created and then instantaneously annihilated. But in the latter case the human mind could not apprehend the substance; for since all human cognitive experience takes place _in time_, which involves _duration_, the mind can apprehend a substance only on condition that the latter has some permanence, some appreciable duration in existence. This fact, too, explains in some measure the error of conceiving permanence as essential to a substance. But the error has another source also: Under the influence of subjective idealism philosophers have come to regard the individual’s consciousness of his own self, the consciousness of the _Ego_, as the sole and unique source of our concept of substance. The passage we have just quoted from Spencer is an illustration. And since the spiritual principle of our conscious acts is a permanent principle which abides throughout all of them, thus explaining the unity of the individual human consciousness, those who conceive substance in general after the model of the _Ego_,