When you saw a new book (for example, a copy of Kepler’s or Galileo’s latest, or the latest Baghdad translation from the ancient Greeks or Romans, you had no way of evaluating its authenticity or legitimacy. It might be a complete fraud. And books were so expensive, and so few people were literate, you couldn’t afford to throw any of them away, even if they contradicted each other.

The Library of Alexandria must have been full of volumes the scholars of the time were familiar with, but didn’t know whether or not to believe unless they were corroborated by other books or by the personal experiences of witnesses.

Now that text is not to be believed, and when imagery, audio and even video is routinely and convincingly faked, all our historical records will be suspect. We’ll not be able to believe anything. Its like modern advertising. No one really believes what advertising copy says about consumer goods, do they?