Alexander Chumakov - Super English Course  Speak like a native стр 13.

A little bit later we see the word intelligent. Intelligent means good at thinking clearly and quickly. When a person is intelligent it means he is good at understanding difficult ideas and subjects. So the history teacher is not only handsome and strong, but he is also good at thinking clearly and quickly. And he can understand difficult things, ideas which other people cannot. Or maybe they can, but not that quickly as the history teacher can. So the history teacher is intelligent.