which identifies mind or self with the “thought-stream,” is equally impotent to account for this sense of our abiding sameness. James’ attempt at a phenomenalistic explanation of the persistent continuity of self, on the assumption that each passing thought knows its receding predecessor and becomes known, in turn, by its successor, is puerile. To pass over other flaws, this absurd theory encounters an insuperable difficulty in _sleep_, which interrupts, for a considerable interval, the flow of conscious thought. Thought is a transient reality, which passes, so far as its actuality is concerned, and can only remain in the form of a permanent effect. Unless, therefore, there were some _persistent medium_ in which the last waking thought could leave a permanent vestige of itself, the process of relaying the past could never be resumed, and we would lose our personal identity every twenty-four hours. The mind, or subject of thought, then, must be an abiding and unitary principle distinct from our composite bodies, and from our manifold and fleeting thoughts. Finally, to the two foregoing attributes of the human soul (substantiality and simplicity), we must add a third and crowning attribute, namely, _spirituality_. It is this, and this alone, that differentiates the human from the bestial soul, which latter is but an incomplete complement of matter, incapable of existence apart from matter, and doomed to perish with the dissolution of the organism, as the cylindrical form of a candle perishes with the consumption of the wax by the flame.