Second, the education system assumes that once we understand something, it will stick in our minds for as long as we need it to. These minds are envisaged as a little like computer hard drives: unless violently knocked, they will hold on to data for the long term. This is why we might imagine that education could stop at the age of twenty-two, once

Practice. Nelson says, “You don’t get good at something unless you practice. That’s for anything in the world.” So practice remembering things, whether it’s facts about biology for school, to-do lists, or the telephone numbers of your friends (you can amaze them, since almost no one does this anymore).

The answer is that when we can get away with it, we don't think. Instead we rely on memory. Most of the problems we face are ones we've solved before, so we just do what we've done in the past. For example, suppose that next week a friend gives you the candle problem. You would immediately say, “Oh, right. I've heard this one.