Derrida:
A text is not a text unless it hides from the first comer, from the first glance, the law of its composition and the rules of its game. A text remains, moreover, forever imperceptible. Its laws and rules are not, however, harbored in the inaccessibility of a secret; it is simply that they can never be booked, in the present, into anything that could rigorously be called a perception.
The reader has to take them for granted, as an accidental feature of the language. This is why the reader does not notice them at all: he cannot see into their nature. They are like the shadows which appear on the surface of water when you shine a light upon it. The reader who notices these laws and rules must also notice that they do not apply to him. He may have been born with the same eyesight as the author of this book, but his own sight is different. It is not even the same kind of difference. Sight, for him, might be something like a language: it is not a human faculty at all, but a property of human minds, and it is strictly relevant to the thing called vision. He might be able to read this book, if he could master the visual code the author has chosen to write in, and if he had access to the equipment that could translate this code into something the reader could see. He might not like what he saw, or he might not understand it. But then, neither would the author of this book.
If, on the other hand, the reader were blind, then this book would be for him like a symphony or a poem: something that he can experience and enjoy without having to understand its logic or its structure. If the reader were deaf as well, then this book would be a braille version of it, something that he could touch and feel, without having to hear its sounds.
Between blind, deaf and seeing readers, there are different kinds of games that the book can be for them. A book can be:
* a mirror. For the seeing reader, the book can function as a mirror. He can enter into its world, as if he were a character in a book. The book can give him a new perspective on the world, showing him things he had not seen before. He can look at the world through the eyes of another, as it were, and enjoy a richer vision of events in his own life. This is a particular kind of pleasure, and the reader should take it seriously, since it can be very moving to experience events through the eyes of another.
* a door. For the hearing reader, the book can function as a door. It can offer him an invitation to enter another world, a different dimension, where the normal rules of reality do not apply. It is the privilege of the seeing reader to step into the world of the book; the reader of the hearing type should only use the book when he can't find anyone to read the sign language with.
* a prison. For the blind reader, the book can be a prison. It can give him a sense of frustration and powerlessness at a world that he feels should be working but is not. It can also give him a sense of pity for the seeing reader, and a desire to hit him, since the seeing reader has all the advantages, and the blind reader does not.
* a weapon. For the reader who is both blind and deaf, the book can be a weapon. It is up to the reader to decide how he will use it: as a weapon of physical violence, verbal abuse or intellectual seduction.
These are only some of the possible meanings that a book can have.