What does Tim O'Brien think about now and then. What does he see?

O'Brien thinks about the young man and sees him walking our of the morning fog.

Even now I haven't finished sorting it out. Sometimes I forgive myself, other times I don't. In the ordinary hours of life I try not to dwell on it, but now and then, when I'm reading a newspaper or just sitting alone in a room, I'll look up and see the young man coming out of the morning fog. I'll watch him walk toward me, his shoulders slightly stooped, his head cocked to the side, and he'll pass within a few yards of me and suddenly smile at some secret thought and then continue up the trail to where it bends back into the fog.