Time Quotes (page 12)
Time is so strange and life is twice as strange. You must promise me not to live to be too old, William. It if is at all convenient, die before you're fifty. It my take a bit of doing. But I advise this is simply because there is no telling when another Helen Loomis might be born. It would be dreadful, wouldn't it, if you lived on to be very very old and some afternoon in 1999 walked down Main street and saw me standing there, aged twenty-one, and the whole thing out of balance again?
Ray Bradbury