Have you ever wondered what your memory process is? How is it, you learn things then you recall things you already learned, or even: how is it that your memory of something past is not necessarily the same as what really happened?
Well, even without that pondering, here is a simple, non correctly timed, animated example of memory in the brain. What it does not show is that each value represented by the balls, and contained within them gets smaller as it goes down the ladder, and remains nearly the same as it goes up the ladder. This is how your memory lets you recall things you already knew, and keeps them in perspective of nearly when you knew them.