tory nerves are not sensitive to air-waves, sees the clouds
move and the trees sway, the brook ripple and the trumpeter with his
tube at his lips; but the air-waves they all create pass by him, and
sound is inconceivable. That sound is a mere nervous sensation is
further proved by the fact that we have disturbances of the auditory
nerve which we call singing in the ears. No waves of air create this
disagreeable music. It arises from some affection of the nerve, which
irritates it to a vibration similar to that which it undergoes when
air-waves of a certain intensity reach it.

We say the sound rolled on, the odor was wafted, the color was printed,
our language and our thoughts implying that the sound, the odor, the
color, are things, when in reality they are all mere sensations,
answering to the touch of physical agents. All sensation is
nerve-motion. Outer stimulus, applied to the nerves, causes contractions
which, communicating with the brain, give the idea of color or taste or
sound.

The sense of feeling is a recognition of the existence of objects by a
duller perception than the others, though all of the senses attain their
perceptions by feeling, in the strict meaning of the word. We say things
feel hard or soft, the varying density of the objects being the cause of
the varying sensations they awaken. Smoothness and roughness are varying
outlines of surface, existing as physical conformation; the pleasurable
or disagreeable sensations awakened in us by contact being due to the
greater or less irritation of the nerves of feeling that attrition with
it occasions. Motion is absolutely necessary to give us an ides of the
density or configuration of an object. The mere touch of that object is
insufficient to possess us with its nature. Iron and down are
indistinguishable, unless we, to a certain extent, manipulate them.
Glass would be indistinguishable from sand-paper did we not to a certain
extent pass our fingers over the different surfaces. Mere touch would
not suffice. We have the evidence of all of our senses to prove to us
the nature of an object. It tastes or smells or vibrates or is colored;
the varied sensations thus awakened combining to give us our totality of
conception. The rose reflects light-waves which the eye feels red; it
emits oil-particles which the nose feels fragrant; it touches our
tongue, and feels pleasantly; it touches our fingers, and feels soft and
smooth. It exists in nature as a physical