A few words from Sartre:
A book has its absolute truth in its own time. It is lived like a riot or a famine, with much less intensity of course, and by fewer people, but in the same way. It is an emanation of intersubjectivity, a living bond of rage, hatred, or love between those who have produced it and those who receive it. If it gains ground, thousands of people reject it and deny it: we all know very well that to read a book is to rewrite it. At the time it is first a panic, an escape, or a courageous affirmation; at the time it is a good or a bad action. Later, when the time has died, it will become relative; it will become a message. But the judgement of posterity will not invalidate the opinions men had of it during its lifetime. . . .