33 o THE POPULAR SCIENCE MONTHLY. 



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 ac- 

 tion 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 be- 

 tween 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 un- 

 recognized ; but to conclude that therefore thought is a purely mate- 

 rial 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 noth- 

 ing 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, Moliere, or Shake- 

 speare, 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 ma- 

 terial 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 labora- 

 tory where such combinations are being constantly made as never 

 Wohler 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 uni- 



