hich it
is, and not the finger or hand, that really feels when the one is hurt,
or when anything comes in harmless contact with the other. To prove
this, let the fine nervous threads, which, running up the whole length
of the arm, connect the skin of the finger with the spinal marrow and
brain, be cut through close to the spinal cord, and no pain will be
felt, whatever injury be done: while if the ends which remain in
connection with the cord be pricked, the sensation of pricking in the
finger will arise just as distinctly as before. Or let a walking-stick
be held firmly by the handle, and its other end be touched, and the
tactile sensation will be experienced as if at the end of the stick,
where, however, it plainly cannot be. It is the mind alone which feels,
but which, by a peculiar faculty of localisation or extradition, seems
to remove a feeling exclusively its own, not only to the outside of
itself, but to the outside also of the walls of its fleshly tenement.
And as it is with pain or touch, so it is with every sensation with
which any of the so-called secondary qualities of matter are identical.
If I look at, or smell, or taste a blood orange, the sensation of
colour, or scent, or flavour I receive is entirely and exclusively my
own, the orange remaining quite unconscious of its own redness, or
fragrance, or sweetness, and not, indeed, possessing in itself any real
qualities of the kind. For to take redness as an example; how does the
sensation of it or of any other colour arise? The waves of a certain
very attenuated medium, the particles of which are vibrating with vast
rapidity but with very different velocities, strike upon an object and
are thrown off in all directions. Of the particles which vibrate with
any particular velocity, some are gathered by the optical apparatus of
the eye, and deflected so as to impinge on the retina and on the fibres
of the optic nerve therewith connected, producing in these fibres a
change which is followed by other changes in the brain, which, again, by
virtue of some inscrutable union between the brain and the mind, create
a feeling or consciousness of colour. What the particular colour shall
be, depends either on the rate of motion in the vibrating medium or on
the character of the retina; and if, while the former remained the same,
the other were to be altered, or if two persons, with differently formed
retinas, and one of the two colour-blind, were to be looking, what had
f