PROLOGUE At least twice a year, you and everyone else should take leave from heavy-duty living, check the fishing gear, and keep watch for any passing jacks. The truce won't affect life's outcome too much, and you may not catch any fish; but at least it will demonstrate your continuing interest in being human and not a robot. Our personal choices for philosophical beach combing are two very significant anniversaries: New Year's Day, when good ideas and resolutions abound, and we're full of optimism for the future. The early mornings of our Birthdays, when we pessimistically wonder how much...