" 
f 
158 MR. DARWIN’S CRITICS v 
which goes on in the nervous system of the man. 
Unless the nerve-elements of the retina, of the. 
optic nerve, of the brain, of the spinal cord, and 
of the nerves of the arms, went through certain. 
physical changes in due order and cortdlation, the 
various states of consciousness which have been 
enumerated would not make their appearance. So 
that in this, as in all other intellectual operations, 
we have to distinguish two sets of successive 
changes—one in the physical basis of conscious- 
ness, and the other in consciousness itself ; one set 
which may, and doubtless will, in course of time, 
be followed through all their complexities by the 
anatomist and the physicist, and one of which only — 
the man himself can have immediate knowledge. — 
As it is very necessary to keep up a clear 
distinction between these two processes, let the one 
be called newrosis, and the other psychosis. When 
the gamekeeper was first trained to his work 
every step in the process of neurosis was accom-_ 
panied by a corresponding step in that of psychosis, 
or nearly so. He was conscious of seeing some- 
thing, conscious of making sure it was a hare, 
conscious of desiring to catch it, and therefore to 
loose the greyhound at the right time, conscious of 
the acts by which he let the dog out of the leash. 
But with practice, though the various steps of the 
neurosis remain—for otherwise the impression on 
the retina would not result in the loosing of the 
dog—the great majority of the steps of the 
