SCIENTIFIC MATERIALISM 93 



lem, which differs from the problems of ordinary mechan- 

 ics, in the smallness of the masses, and the complexity 

 of the processes involved. Here you have one half of 

 our dual truth; let us now glance at the other half. As- 

 sociated with this wonderful mechanism of the animal 

 body we have phenomena no less certain than those of 

 physics, but between which and the mechanism we dis- 

 cern no necessary connection. A man, for example, can 

 say, "I feel," "I think," "I love"; but how does con- 

 sciousness infuse itself into the problem ? The human 

 brain is said to be the organ of thought and feeling: 

 when we are hurt, the brain feels it; when we ponder, 

 or when our passions or affections are excited, it is 

 through the instrumentality of the brain. Let us en- 

 deavor to be a little more precise here. I hardly imag- 

 ine there exists a profound scientific thinker, who has 

 reflected upon the subject, unwilling to admit the ex- 

 treme probability of the hypothesis, that for every fact 

 of consciousness, whether in the domain of sense, 

 thought, or emotion, a definite molecular condition, of 

 motion or structure, is set up in the brain; or who 

 would be disposed even to deny that if the motion, or 

 structure, be induced by internal causes instead of ex- 

 ternal, the effect on consciousness will be the same ? Let 

 any nerve, for example, be thrown by morbid action into 

 the precise state of motion which would be communicated 

 to it by the pulses of a heated body, surely that nerve 

 will declare itself hot the mind will accept the subject- 

 ive intimation exactly as if it were objective. The retina 

 may be excited by purely mechanical means. A blow on 

 the eye causes a luminous flash, and the mere pressure of 

 the finger on the external ball produces a star of light, 



