My aunt has a story about this: one time she listened to a Feynman talk on tape. Afterwards she was explaining it to her son and she started to draw out some d

My aunt has a story about this: one time she listened to a Feynman talk on tape. Afterwards she was explaining it to her son and she started to draw out some diagrams that Feynman had been drawing on the board during the lecture. Her son said "Wait, weren't you just listening to this? How do you know what the diagrams looked like?" She realized that his explanations were so clear that she had been able to picture everything without even consciously thinking about it.