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 why our consciousness coincides, in certain circumstances, with the actions of the brain, and, in others, does not come near them. In other words, it contains an explanation of the unconscious. I can show this by quoting certain exact facts, of which the explanation has been hitherto thought to present difficulties, but which become very easy to understand on the present hypothesis. The first of these facts relates to the psychology of the motor current. This current has been a great feature in the studies which have been made on the feeling of effort and on the physical basis of the will. The motor current is that which, starting from the cerebral cells of the motor region, travels by way of the fibres of the pyramidal tract into the muscles of the body; and it is centrifugal in direction. Researches have been made as to whether we are or may be conscious of this current; or rather, the question has been put in somewhat different terms. It has been asked whether a psychological state can be the counterpart of this motor current,—if, for example, the feeling of mental effort produced in us at the moment of executing a difficult act or of taking a grave resolution, might not have this motor current for a basis.

The opinion which has prevailed is in the negative. We have recognised—a good deal on the faith of experiment, and a little also for theoretical