The aging process is a part of most of our lives, and it remains one we try to ignore until it seems to pounce upon us. We evade all its signals. We stay blandly unprepared for some of its obnoxious effects, even though we have coped with the cracked voices and puzzling glands of our emerging natures, and have been guided no matter how clumsily through budding love-pains, morning sickness, and hot flashes. We do what our mentors teach us to do, but few of us acknowledge that the last years of our lives, if we can survive to live them out, are as physically predictable as infancy's or those of our full flowering. This seems impossible, but it is true.