The value of books is proportionate to what may be called their plasticity — their quality of being all things to all men, of being diversely moulded by the impact of fresh forms of thought. Where, from one cause or the other, this reciprocal adaptability is lacking, there can be no real intercourse between book and reader. In this sense it may be said that there is no abstract standard of values in literature: the greatest books ever written are worth to each reader only what he can get out of them. The best books are those from which the best readers have been able to extract the greatest amount of thought of the highest quality; but it is generally from these books that the poor reader gets least.
-Edith Wharton, The Vice of Reading