Sometimes we get sad about things and we don’t like to tell other people that we are sad about them. We like to keep it a secret. Or sometimes, we are sad but we really don’t know why we are sad, so we say we aren’t sad but we really are.

学得越多，知道得越多。知道得越多，忘得越多。忘得越多，知道得越少。那何必学习呢？