Page:Popular Science Monthly Volume 4.djvu/344

330 express an actual physical reality. The processes by which the brain and the body are nourished, as well as those which produce gradual exhaustion when either is employed for a long time or on arduous work, not only correspond with each other, but are in fact identical in their nature; so that Jeremy Taylor anticipated a comparatively recent scientific discovery when he associated mental and bodily action in the well-known apothegm, "Every meal is a rescue from one death and lays up for another; and while we think a thought we die." This is true, as Wendell Holmes well remarks, "of the brain as of other organs: the brain can only live by dying. We must all be born again, atom by atom, from hour to hour, or perish all at once beyond repair."

And here it is desirable to explain distinctly that the relations between mind and matter which we are considering are not necessarily connected with any views respecting the questions which have been at issue between materialism and its opponents. We are dealing here with the instrument of thought, not with that, whatever it may be, which sets the instrument in motion and regulates its operation. So far, indeed, as there is any connection between physical researches into the nature of the brain or its employment in thought, and our ideas respecting the individuality of the thinker, the evidence seems not of a nature to alarm even the most cautious. Thus, when Mr. Huxley maintains that thought is "the expression of molecular changes in that matter of life which is the source of our other vital phenomena," we are still as far as ever from knowing where resides the moving cause to which these changes are due. We have found that the instrument of thought is moved by certain material connecting links before unrecognized; but to conclude that therefore thought is a purely material process, is no more necessarily just than it would be to conclude that the action of a steam-engine depends solely on the eccentric which causes the alternation of the steam-supply. Again, we need find nothing very venturesome in Prof. Haughton's idea, that "our successors may even dare to speculate on the changes that converted a crust of bread, or a bottle of wine, in the brain of Swift, Molière, or Shakespeare, into the conception of the gentle Glumdalclitch, the rascally Sganarelle, or the immortal Falstaff," seeing that it would still remain unexplained how such varying results may arise from the same material processes, or how the selfsame fuel may produce no recognizable mental results. The brain does not show in its constitution why such differences should exist. "The lout who lies stretched on the tavern-bench," says Wendell Holmes, "with just mental activity enough to keep his pipe from going out, is the unconscious tenant of a laboratory where such combinations are being constantly made as never Wöhler or Berthelot could put together; where such fabrics are woven, such colors dyed, such problems of mechanism solved, such a commerce carried on with the elements and forces of the outer