How can I respond?

I know this fantastically gifted art professor - he is just amazingly talented and really knowlegable with regard to theory and practice. The problem is this: he has the most debilitating stammer that I've ever seen. When we talk, I want to encourage him to express himself without seeming to patronize his crippling condition. He DOES seem to level out when he's speaking of something that truly piques his interest, but during lectures (poor guy), it can take up to 3 minutes for him to get unstuck on a word.

Any suggestions would be GREATLY appreciated. And, I wanna slap the crap out of the rude and cruel students who roll their eyes and demonstrate blatant intolerance. But for the Grace of God, there go I! Tweet