I wonder what song he is playing. Something taught to him in his childhood?
A few years ago I had a chance to play around on a piano. Without sheet music, all I could recall was the first song I ever memorized, for the first recital I ever did: Mary Had a Little Lamb. I remembered, even, the harmonic accompaniment to the melody, though I couldn't tell you know what that type of chord was called. My body recalls what my mind does not. It has been so long since I've really played - almost twenty years - could I even read sheet music any more? It'd be a struggle, I think.
There's an analogy for life in that.