154 HUXLEY 



The senses are the gateways of knowledge, and we 

 assume that impulses vibrating from without enter 

 these, and are conveyed by the nerves to the central 

 nervous system — the seat of consciousness, or of 

 knowledge of what goes on in the mind. We see, 

 we smell, we hear, we taste, we touch ; but the 

 colour, the scent, the sound, the flavour, the hardness 

 or softness, the warmth or coldness, are not in the 

 things which we assume to be the cause of these sen- 

 sations. They are in what is called " states of con- 

 sciousness." How the passage is effected from the 

 nerve-cells to consciousness we have no means of 

 knowing. The thing is an insoluble mystery. The 

 mutual dependence of what we call the body and 

 what we call the mind is certain. We know nothing 

 of mind apart from matter. We know that the brain 

 is the organ of thought, and we cannot conceive of 

 changes in the nerve-cells being produced by con- 

 sciousness, so that the psychical seems wholly sub- 

 ordinate to the physical. Every feeling, every 

 thought, is accompanied by molecular changes, and 

 Huxley expressed the belief, which the "new psy- 

 chology " may justify, that " we shall, sooner or later, 

 arrive at a mechanical equivalent of consciousness, 

 just as we have arrived at a mechanical equivalent of 

 heat." l That marvellous faculty by which things are 



1 Coll. Essays, i. p. 19 1. 



