For most people, we know the essential boundaries of their lives. Born on this date, died on that one. With my dad, this doesn't work. I know when he was born, but it's hard to say exactly when he left us. His departure has been a process more than a moment. His body is still present and functioning fairly well, but his mind is mostly gone. Sometimes he knows who I am. More often he does not. On a good day, he can converse lucidly about his childhood. He can sound so convincing when he mentions being visited this morning by his own father, a man who died decades ago. Some information he simply cannot process. For example, he believes himself to be much younger than he actually is. I like to think he has retreated mentally to a happier time--when he was vigorous, my mother was beautiful, and he could do things he enjoyed. Now instead of building things--his passion--he sleeps most of the time. Rest peacefully, Daddy.