Those that know, do. Those that understand, teach.

Knowing how to do something and understanding why it works are separate kinds of mastery. Plenty of skilled practitioners cannot explain their own skill, because it lives in their hands rather than their words. Teaching requires pulling that knowledge apart and seeing its structure, which in some ways is a deeper grasp. Explaining something well is therefore more than a consolation for those who cannot do it.

Try teaching a skill you perform well to someone who lacks it. Notice where you struggle to explain what you do. Those gaps show what you know without understanding, and filling them usually improves the doing as well.