Learning is remembering and understanding. You have to progressively build layers of understanding (and be able to recall it quickly). This article focuses mos

Learning is remembering and understanding. You have to progressively build layers of understanding (and be able to recall it quickly). This article focuses mostly on the second part, about remembering. You could recall things but you may not fully understand it, which is going to make it harder to learn. And of course, you might understand something, but eventually you will forget it (either few days or few years, depending on how often you use related memory). When you forget, it makes it hard to learn.