Waving to the Blind Man

There is a blind man who walks around the streets surrounding the campus where I live. Every time I pass him while driving in my car, he waves.

I always wave back.

Important questions to consider:
Why am I waving to the blind man?

More importantly:
Why does the blind man always wave at me?

I hope one day I can give that much with no idea of the outcome. I'm beginning to see teaching in this light - waving in the figurative dark, blind to the ways a smile or kind word may facilitate some positive reaction in the future that I might never know.

The blind man seems happy, though.