I guess he was just one of the average doctors then. It takes a lot to think on your feet, to have a lot of things that are not notable by others come together to form the right thought/response.

I used to be able to think pretty quick on my feet because of my job. While I may not be a genius or even slightly above average in intelligence, I was/still am to an extent, able to still think on my feet.

An average teacher will not notice when they are losing the classes attention, an above average teacher will see the hidden signs and make adjustments to keep the class interesting for the students and keep their attention.