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, 



