The Earth revolves around the Sun, and you learn a language by using it

The current/past thought in language learning is that you learn a language so you can use it. But in reality you use a language so you can learn it.

It's like thinking the Sun revolves around the Earth, and not the other way around. Not true, and difficult to see at the beginning because it appears that it is the Sun that is moving - appears that you need to learn a language before you can use it.

But once you see it the way that it actually is, you can't un-see it.