content or confines of our awareness, stored up, so to speak, ready for future use, the mass of our past mental experiences. Here you would find, perhaps, the visualized idea of a seagull soaring over the waters of your beautiful bay conserved in association with the idea of the mathematical formula, a + b = c; the one having originated in a perception of the outer world through the window of your study while you were working at a lesson in algebra which gave rise to the latter. And yet conserved as ideas, as such vast numbers of experiences would be, we should not be aware of them until they were brought by some mysterious agency into the consciousness of the moment. The great mass of the mental experiences of our lives which we have at our command, our extensive educational and other acquisitions from which we consciously borrow from time to time, as well as those which, we have seen, are conserved though they cannot be voluntarily reproduced, all these mental experiences, by the hypothesis, would still have persisting conscious existences in their _original concrete psychological form_. Such an hypothesis, to my mind, is hardly thinkable, and yet this very hypothesis has been proposed, though in less concrete form perhaps, in the doctrine of the “subliminal mind,” a particular form of the theory of the subconscious mind. This doctrine, which we owe to the genius of the late W. H. H. Meyers, has more recently appeared, without full recognition of its paternity, in the writings of a more modern school of psychology. According to this doctrine our personal consciousness, the ideas which we have at any given moment and of which we are aware, are but a small portion of the sum total of our consciousness. Of this sum-total we are aware, at any given moment, of only a fractional portion. Our personal consciousness is but sort of up-rushes from this great sum of conscious states which have been called the subliminal mind, the subliminal self, the subconscious self. These conscious up-rushes make up the personal “I,” with the sense of awareness for their content. The facts to be explained do not require such a metaphysical hypothesis. All that is required is that our continuously occurring experiences should be conserved in a _form_, and by an arrangement, which will allow the concrete ideas belonging to them to reappear in consciousness whenever the conserved arrangement is again stimulated. This requirement, the theory of conservation, which is generally accepted by those who approach the problem by psycho-physiological methods, fully satisfies. Before stating this theory in specific form let me mention to you still another variety of the subliminal hypothesis, metaphysical in its nature, which appeals to some minds of a philosophical tendency.