Because we do not know when we'll die. We get to think of life as an inexastable will. And yet everything only happens a certain number of times. And a very small number realy. How many more times will you remember a curtain afternoon in your childhood? An afternoon that is so deeply part of your being. That you can't even conceave your life without it. Perhaps 4 or 5 times more. Perhaps not even that. Or how many more times will you watch the full moon rise? Perhaps 20. And yet it all seems limitless.