of his fellows, he would have no means of imagining
what they think. Since the mind of the sightless is essentially the same
as that of the seeing in that it admits of no lack, it must supply some
sort of equivalent for missing physical sensations. It must perceive a
likeness between things outward and things inward, a correspondence
between the seen and the unseen. I make use of such a correspondence in
many relations, and no matter how far I pursue it to things I cannot
see, it does not break under the test.

As a working hypothesis, correspondence is adequate to all life, through
the whole range of phenomena. The flash of thought and its swiftness
explain the lightning flash and the sweep of a comet through the
heavens. My mental sky opens to me the vast celestial spaces, and I
proceed to fill them with the images of my spiritual stars. I recognize
truth by the clearness and guidance that it gives my thought, and,
knowing what that clearness is, I can imagine what light is to the eye.
It is not a convention of language, but a forcible feeling of the
reality, that at times makes me start when I say, "Oh, I see my
mistake!" or "How dark, cheerless is his life!" I know these are
metaphors. Still, I must prove with them, since there is nothing in our
language to replace them. Deaf-blind metaphors to correspond do not
exist and are not necessary. Because I can understand the word "reflect"
figuratively, a mirror has never perplexed me. The manner in which my
imagination perceives absent things enables me to see how glasses can
magnify things, bring them nearer, or remove them farther.

Deny me this correspondence, this internal sense, confine me to the
fragmentary, incoherent touch-world, and lo, I become as a bat which
wanders about on the wing. Suppose I omitted all words of seeing,
hearing, colour, light, landscape, the thousand phenomena, instruments
and beauties connected with them. I should suffer a great diminution of
the wonder and delight in attaining knowledge; also--more dreadful
loss--my emotions would be blunted, so that I could not be touched by
things unseen.

Has anything arisen to disprove the adequacy of correspondence? Has any
chamber of the blind man's brain been opened and found empty? Has any
psychologist explored the mind of the sightless and been able to say,
"There is no sensation here"?

I tread the solid earth; I breathe the scented air. Out of these two
experiences I form numberless associa