A teacher is better than two books

He who teaches a boy teaches three: a youth, a young man, and an old man

The teacher is like the candle, which lights others in consuming itself

To teach is to learn.

Teaching is reminding others that they know just as well as you. You are all learners, doers and teachers.

That is the difference between good teachers and great teachers: good teachers make the best of a pupil's means; great teachers foresee a pupil's ends.