Not Quite Right

My PHIL105 lecturer is blind. I found this out when I went up to him after today's lecture, to tell him a joke. Up until this point I'd been completely unaware of this fact, and only know now because I've been around enough blind people to pick up on the facial mannerisms - not looking at a person who's talking to you, for example, as well as the blemished corneas.
It shouldn't surprise me, but I'd never even considered that he might be visually-impaired. His stance at the podium, the way he interacts with the other lecturer (I now understand why there is another lecturer), and his general demeanour give no clues. Truly a great example of how a disability doesn't have to end one's prospects of having a career and a life.