Once upon a time C. S. Lewis wrote an essay entitled, On The Reading Of Old Books. In it, he advises reading old books to avoid becoming conditioned exclusively by your own time. To quote: "It is a good rule, after reading a new book, never to allow yourself another new one till you have read an old one in between. If that is too much for you, you should at least read one old one for every three new ones."
I like this advice because I tend to prefer old books to new ones, but I would think it sound advice even if I preferred reading new books. What brought this essay to mind was a recent story about the republication of Mark Twain's writings in a sanitized form, removing words deemed to be racially offensive and perhaps some other revisions. This is not the first time stories like this have appeared. Several years ago, there were stories of Lewis' own Chronicles Of Narnia being reissued in a version that had their Christian imagery expunged.
It seems to me not only silly, but the height of presumption to alter the work of someone else without his approval. Any modern revisionist that took it upon himself to "update" the Mona Lisa by putting a tattoo on her or adding an outboard motor to Charon's boat would be recognized for the criminal, iconoclastic kook that he was. When Ted Turner's outfit - I know not which one, TCM perhaps - started colorizing old black and white movies there was more objection than I have seen to altering the written works of the past. Colorization changes the appearance, but not the content of the work; changing the wording changes the message and deprives the reader of a vicarious excursion into the past. As Lewis says, "Every age has its own outlook. It is specially good at seeing certain truths and specially liable to make certain mistakes. We all, therefore, need the books that will correct the characteristic mistakes of our own period."
Our age is afflicted with what I call "chronological snobbery" - the belief that all our predecessors were mired in ignorance, prejudice, superstition, gullibility and all that is bad or harmful. It's amazing that such benighted people should have produced such enlightened progeny. Fortunately they did, and now we can correct all their errors; but correcting their errors will deprive subsequent generations of discovering our perfection.
Where books are concerned, age is a pretty good test of worth. Plato, Dante and St. Augustine will probably still be read in five-hundred years, whereas Paul Ehrlich probably won't; but if we "update" the first three they will lose their value.
In Aldous Huxley's Brave New World, Mustapha Mond has a vault in which he keeps forbidden books. If the modernizing biblioclasts continue their work, future readers will need to find that vault.