mankind, do not remain the property of the philosophers. They ooze out into general literature and become, so to speak, the common property of mankind. In the present instance, we find in the attitude of the majority of the cultivated persons who surround us to-day unmistakable traces both of the crude materialism which seems so natural to man when he first begins to think about the mind, and of the line of speculation indicated above. Men think of the mind as somehow in the body, in the brain; and yet they are not willing to admit that it is unequivocally in the body—in it as brain cells are, as blood corpuscles are, as are any of the material constituents of the body itself.
Ask the average undergraduate student—who can not be accused of having done much thinking for himself, but who holds the vague opinions that he has absorbed from those about him—ask him where his mind is, and he will probably answer that it is in his brain. Ask him, further, whether there is any hope of getting at it as one may hope to get at the material constituents of the brain, and I think he will say, No! It is there, and yet not exactly there; it is there in a Pickwickian sense. He feels as Dr. Leidy did, and his feeling has exactly the same foundation. It rests upon an ancient tradition.
What, then, is the relation of mind and brain? We seem to be left with an 'in' on our hands that is not really an in at all, but is something else. What is it? Our student can not tell us, nor can those from whom he has picked up his vague and inconsistent notions.
To those who wish to think clearly all this is naturally unsatisfactory. Those who busy themselves with the problem "are impelled to try to make the matter less vague. Now and then, even in our time, men go back, to accomplish this end, to something very like the ancient materialism which the world outgrew so long ago.
Thus we now and then hear it maintained that thought is a secretion of the brain. Half a century ago much was said about this, and to many the doctrine seemed plausible. It certainly does appear to make clearer the relation of mind and body, if we hold that mental phenomena are related to the brain as the saliva is related to the salivary gland. If we can say this, we may maintain that the mind is in the body in a literal and unambiguous sense of the word.
But may we legitimately speak thus? The secretion of a gland is a something so unequivocally material that it can be treated just like other material things. It can be collected into a test-tube and analyzed by the chemist. Has any one ever succeeded in filling a test-tube with mental phenomena? in bottling and analyzing in a laboratory pains and pleasures, memories and anticipations? Dr. Leidy, who knew a vast amount about the secretions of glands, did not confound ideas with secretions, and would not even attempt to treat them in the same way.