LIMITS OF OUR KNOWLEDGE OF NATURE, 31 



looked the fourth and simplest supposition, viz., that perhaps the 

 watches, whose simultaneous action is to be accounted for, may be 

 after all only one. Whether we shall ever understand mental phe- 

 nomena from their material conditions is a very different question 

 from that other, viz., whether these phenomena are the product of ma- 

 terial conditions. The former question might be decided in the neg- 

 ative without in the least affecting the latter, to say nothing of 

 negativing it. 



In the passage we have already cited, Leibnitz asserts that a mind 

 incomparably higher than the human mind, but yet finite, could, if it 

 were possessed of senses and technical powers of like perfection, form 

 a body capable of mimicking the actions of man. He does not say 

 that a man could be formed, for in his view the automaton of flesh 

 and bone, which he regards as soulless, even as Descartes regarded 

 all animals, still lacks the mechanically-incomprehensible soul-monad. 

 The difference between Leibnitz's point of view and our own be- 

 comes very evident here. Imagine all the atoms whereof Caesar was 

 made up at a given moment, say as he stood at the Rubicon, to be 

 by mechanical power brought together, each in its own place, and 

 possessed of its own velocity in its proper direction. In our, view 

 Caesar would then be restored mentally as well as bodily. This arti- 

 ficial Caesar would at the first instant have the same sensations, ambi- 

 tions, imaginings, as his prototype on the Rubicon, and the same 

 memories, the same inherited and acquired faculties, etc. Suppose 

 several artificial figures of the same model to be simultaneously formed 

 out of a like number of other carbon, hydrogen, etc., atoms. What 

 would at the first moment be the difference between the new Caesar 

 and his duplicate, beyond the differences in the places where they 

 were formed ? But the mind imagined by Leibnitz, after fashioning 

 the new Caesar and his many Sosiae, could never understand how the 

 atoms he himself had disposed in order, and set into action with 

 proper velocity, could give mental activity. 



Take Carl Vogt's bold expression, which in 1850 introduced a sort 

 of mental tournament : " All those capacities which we call mental 

 activities are only functions of the brain ; or, to use a rather homely 

 expression, thought is to the brain what the bile is to the liver, or the 

 urine to the kidneys." The unscientific w^orld were shocked at the 

 simile, considering it to be an indignity to compare thought with 

 the secretion of the kidneys. Physiology knows no such aesthetic 

 discriminations of rank. In the view of physiology the kidney secre- 

 tion is a scientific object of just the same dignity as the investigation 

 of the eye, or the heart, or any so-called " nobler " organ. Nor is 

 Vogt's expression worthy of blame on the ground that it represents 

 mental activity as being the result of material conditions in the brain. 

 Its faultiness lies in this, that it leaves the impression on the mind 

 that the soul's activity is in its own nature as intelligible from the 



