=Psycho-physical parallelism and monism.=—According to the doctrine of psycho-physical parallelism every mental process is correlated with (accompanied by) a brain process. As brain processes thus viewed are “unconscious” (in the sense of not having the attribute of consciousness) we may express this in other terms and say: every “conscious” process is accompanied by an “unconscious” process. I have no intention of entering here into the question of the validity of the doctrine of psycho-physical parallelism. I wish merely to point out that if parallelism is a true formulation of the mind-brain problem, as I have just stated it, the converse ought to hold true, namely, that every brain process of a certain kind involving intelligence ought to be correlated with consciousness. But if some subconscious processes manifesting what is equivalent to thought, reasoning, judgment, imagination, volition, etc., are unconscious—as seems likely if not probable—then this converse does not hold true. This has some bearing on the validity of the doctrine; for if physical processes can perform substantially the same function as conscious intelligence it is difficult to reconcile this fact with what I may call naïve psycho-physical parallelism. It is reconcilable, however, with psychic monism. According to this doctrine it is not a question of parallelism at all. There is only one process—the psychical. The physical brain process is only an aspect or special mode of apprehending this one. All is psychical but not psychological. That which we apprehend in the form of the unconscious is really psychical and hence is capable of performing the same _kind_ of function as it performs when it becomes psychological. It is not at all certain that unconscious processes may not comprise an intelligence possessing faculties identical in kind with those of conscious intelligence and indistinguishable from the latter. Subconscious processes may exhibit perception, cognition, reason, imagination, conation (will), feeling, etc., and it is possible that some of these processes may be correctly interpreted as unconscious. At any rate, from the point of view of monism, whether the real psychical process or, probably more correctly, how much of it shall emerge as a psychological state of consciousness depends upon intrinsic conditions. Though we cannot penetrate within them it is quite conceivable that it is a matter of complexity of synthesization and coöperative activity of psychical energies. This is a most interesting problem closely related to that of awareness and self-consciousness.