ANY general statement is like a cheque drawn on a bank. Its value depends on what is there to meet it. If Mr. Rockefeller draws a cheque for a million dollars it is good. If I draw one for a million it is a joke, a hoax, it has no value. If it is taken seriously, the writing of it becomes a criminal act. [...]

An abstract or general statement is GOOD if it be ultimately found to correspond with the facts.

BUT no layman can tell at sight whether it is good or bad.

Hence (omitting various intermediate steps) … hence the almost stationary condition of knowledge throughout the middle ages. Abstract arguments didn’t get mankind rapidly forward, or rapidly extend the borders of knowledge. (ABC of Reading)