It's hard to understand what's not understandable especially in light of what we never understood to begin with. The sound of the keys made a clicking noise that would have driven an average man crazy, but the lack of preconceptions in this case led to the clack, clack, clack, clack to a tap, tap, tap, tap to a drum beat driven into the heart of the most relevant moments of his life. But he didn't understand what that meant. Reliving moments you thought were gone. Crying again and again for something you thought you were done with. The clacking, the tapping, leading to recall. Perfect, heartbreaking recall.