This conclusion would not be justified. On the contrary, the proposition describing the greenness can communicate to the blind man just as much as they do to a seeing person, namely, that it is something possessing a certain structure or belonging to a certain system of internal relations. Since Content is essentially incommunicable by language, it cannot be conveyed to a seeing man any more or any better than to a blind one. You will say that nevertheless there is an enormous difference between the two: the seeing man will understand the propositions about colour in a way in which the blind man is unable to understand them, and you will add that the first way is the only right way and that the blind man can never grasp the "true meaning" of those propositions.
Nobody can deny the difference of the two cases, but let us carefully examine its real nature. The difference is not due to an impossibility of communicating to the one something which could not be communicated to the other, but it is due to the fact that a different interpretation takes place in the two cases. What you call the "understanding of the true meaning" is an act of interpretation which might be described as the filling in of an empty frame: the communicated structure is filled with content by the understanding individual. The material is furnished by the individual himself, derived from his own experience. The seeing person fills in material supplied by his visual experience, i.e. material he has acquired by the use of his eyes, while the blind person will fill in some other "content", i.e. some material which is acquired by some other sense organ, as the ear, or some of the sense organs located in the skin.
(These different interpretations are possible because, as we pointed out before, almost any material may take any structure. It is well known that psychologists and physiologists try to represent the system of colours in a spatial picture, e.g. a double cone, each point of which is supposed to correspond to a particular shade of colour, and the relations of similarity between the colours are represented by relations of spatial neighbourhood between the points. The whole scheme is nothing but the construction of a system of points whose spatial relations have the same structure as the internal relations between the colours. We know that a blind man is perfectly familiar with the structure of "space", which to him is a certain order of tactual or kinaesthetic sensations. With the help of this material he is able to build
