If man merely sat back and thought about his impending termination, and his terrifying insignificance and aloneness in the cosmos, he would surely go mad, or succumb to a numbing sense of futility. Why, he might ask himself, should he bother to write a great symphony, or strive to make a living, or even to love another, when he is no more than a momentary microbe on a dust mote whirling through the unimaginable immensity of space?