If it is replied that no physiologist, however spiritual his leanings, dreams of supposing that simple sensations require a "spirit" for their production, then I must point out that we are all agreed that consciousness is a function of matter, and that particular tenet must be given up as a mark of Materialism. Any further argument will turn upon the question, not whether consciousness is a function of the brain, but whether all forms of consciousness are so. Again, I hold it would be quite correct to say that material changes are the causes of psychical { 227} phenomena (and, as a consequence, that the organs in which these changes take place have the production of such phenomena for their function), even if the spiritualistic hypothesis had any foundation. For nobody hesitates to say that an event A is the cause of an event Z, even if there are as many intermediate terms, known and unknown, in the chain of causation as there are letters between A and Z. The man who pulls the trigger of a loaded pistol placed close to another's head certainly is the cause of that other's death, though, in strictness, he "causes" nothing but the movement of the finger upon the trigger. And, in like manner, the molecular change which is brought about in a certain portion of the cerebral substance by the stimulation of a remote part of the body would be properly said to be the cause of the consequent feeling, whatever unknown terms were interposed between the physical agent and the actual psychical product. Therefore, unless Materialism has the monopoly of the right use of language, I see nothing materialistic in the phraseology which I have employed.
The only remaining justification which Mr. Lilly offers for dubbing me a Materialist, _malgré moi_, arises out of a passage which he quotes, in which I say that the progress of science means the extension of the province of what we call matter and force, and the concomitant gradual banishment from all regions of human thought of what we call spirit and spontaneity. I hold that opinion now, if anything, more firmly than I did when I gave utterance to it a score of { 228} years ago, for it has been justified by subsequent events. But what that opinion has to do with Materialism I fail to discover. In my judgment, it is consistent with the most thorough-going Idealism, and the grounds of that judgment are really very plain and simple.