There once dwelt, in the region of Naucratis in Egypt, one of the old gods, an inventor, named Theuth. One day he came before Thamus, the king, and presented his newest inventions of calculation, astronomy, geometry and more. But when he came to the invention of writing and said: "Here, O king, is a branch of learning that will make the people of Egypt wiser and improve their memories: my discovery provides a recipe for memory and wisdom," the king answered: "No, Theuth, you have declared the very opposite of its true effect. If people learn this, it will implant forgetfulness in their souls: they will cease to exercise memory because they rely on that which is written, calling things to remembrance no longer from within themselves, but by means of external marks; what you have discovered is not a recipe for memory, but for reminder.

- Socrates (or Plato, or both), on the invention of writing (Quoted from Plato, Phaedrus, R. Hackforth). I first heard this story from a teacher and friend (who later quoted it on his website). It's a good warning about the dangers of being over-reliant on your tools.