75. FALSE THEORIES OF PERSONALITY.—It is plain that conscious _mental activity_ cannot _constitute_ human personality, or subconscious mental activity either, for all activity is of the accidental mode of being, is an _accident_, whereas a person must be a _substance_. Of course it is the self-conscious cognitive activity of the human individual that _reveals_ to the latter his own self as a person: it is the exercise of reflex consciousness combined with memory that gives us the feeling of personal identity with ourselves throughout the changing events of our mental and bodily life. Furthermore, this self-consciousness has its root in the _rational_ nature of the human individual; and rationality of nature is the differentiating principle which makes the subsisting individual a “person” as distinct from a (subsisting) “thing”. But then, it is not the feeling of personal identity that _constitutes_ the person. Actual consciousness is neither the essence, nor the source, nor even the index of personality; for it is only an activity, and an activity which reveals immediately not the _person_ as such, but the _nature_ as rational;(311) nor does the rational (substantial) principle of a composite nature constitute the latter a person; but only the subsistence of the complete (composite) individual nature itself. These considerations are sufficiently obvious; they presuppose, however, the truth of the traditional doctrine already explained in regard to the existence, nature and cognoscibility of _substance_. Philosophers who have misunderstood and rejected and lost this traditional doctrine of substance have propounded many varieties of unsatisfactory and inconsistent theories in regard to what constitutes “person” and “personality”. The main feature of all such theories is their identification of personality with the habitual consciousness of self, or habitual feeling of personal identity: a feeling which, however, must be admitted to include _memory_ in some form, while the function of memory in any shape or form cannot be satisfactorily explained on any theory of the human _Ego_ which denies that there is a human _substance_ persisting permanently as a unifying principle of successive mental states (63-4).