Perhaps a book on flying machines has not been checked out from the local library for over ten years. At the same time the library's patrons are demanding more copies of Tuesdays With Morrie. The library decides to remove the books that have not been checked out in some time, to make room for the books in demand. And perhaps the government won't let the library give these books away without lots of red tape, or a threat to the future budget. The library simply tosses the books in the dumpster. Gone forever is the earliest, detailed, first-hand history of flying machines.
This may seem an extreme example, but it occurs all over the world. John Warnock, the father of Adobe Systems, owns a 1543 edition of Copernicus' De Revolutionibus Orbium Coelestium. This is not simply an artifact to him, he has read the work and was amazed by Copernicus.
His argument for the earth's rotating around the sun, considering the tools he had and the observations he made, was absolutely compelling. He did it masterfully. In a modern textbook, you don't get that. You get, "Copernicus suggested that the planets rotate around the sun."Even if the pure knowledge Copernicus possessed is no longer of use, even if his tools are long outdated, we can still learn something that seems to be diminishing in our modern society: critical thinking. Knowledge only of the end result will prevent a child from following the process of discovery, from replicating the experiments, from learning, not about the world itself, but how to think about the world.
The ancient Egyptians possessed knowledge which is no longer with us. So did the Mayans, and probably any other lost civilization. What could we do with that knowledge? How would that knowledge affect our way of living? Adaptation to change has made man the most successful animal on the planet. If we continue to dispose of knowledge that no longer seems useful, will changes present ever greater challenges? Might we regress and have to start over, as surely as those who succeeded the Egyptians and Mayans did? Fantastical as it may seem to us now, could a Planet of the Apes scenario threaten our future?