The Mind. 1001 



tion, it follows that the rise of sensation depends, like other modes of 

 motion, on the constitution and form of the matter concerned in its 

 production. 



Each sensation being motion, and a continuation of antecedent mo- 

 tion, it necessarily ceases the moment the antecedent motion stops. When 

 the sensation is revived as memory, it is still in consequence of an ante- 

 cedent motion or stimulation coming from another part of the brain or 

 nervous ganglia, and it stops at the instant such stimulation stops. 

 The mind being made up of sensations, and the secondary products of 

 sensations (as shown in previous chapters), it disappears whenever the 

 stimulations adapted to produce the sensations cease. When a man is 

 asleep, his mind has nearly all disappeared. The machmer}" is there 

 in the shape of the brain and nervous system, for the reproduction 

 of the mind just as soon as the energ}' is applied again to the machine. 

 The mind may be compared to an electric light, the brain to the dynamo 

 by which it is produced. When force is applied to drive the dynamo, 

 the light flashes into existence. When the dynamo is still, there is no 

 light. So when the brain is still, there is no mind. To make the com- 

 parison more exact however, the brain is a multitude of dynamos, each 

 one when running producing a different colored light, that is, a different 

 sort of sensation. They are never all running at once, rarely more 

 than one or two at the same moment, so tha.t in reality only a small 

 amount of mind is in existence or on exhibition at one time. Of the 

 rest we can only say that the potentiality of it exists in brain cells fitted 

 for its production when the proper force is applied, but, until it is ap- 

 plied, it no more exists than does the electric light while the 

 dynamo is at rest. In fact the principle which underlies mental action 

 is precisely that which governs the motions called light and electricity, 

 and the immediate agent whose motions constitute them all is the same 

 universal ether, its different manifestations depending upon the differ- 

 ent forms of ponderable bodies with which it is associated; viz., carbon 

 points for the light, the iron dynamo for the current electricity, and the 

 brain for the mind. 



The comparative natural history of mind no doubt corresponds with 

 the comparative anatomy of the brain and nervous system. Of the 

 three departments of mind, we trace reflex action to the lowest of the 

 animals, and some plants. The lower departments of thought, such as 

 perception, are found in all animals possessed of external sense organs; 

 ej'es, auditory and olfactory organs. Sensibilit3 T , too, must be attributed 

 to animals very low in the scale of being. The sort of sensibility that 

 is common to almost all animals arises from the conditions of the vege- 

 tative sj'stem, especially the stomach. Animals may have sensibility 

 from this cause before they possess acute sensations relating to the en- 



