The whole procedure of his thinking, Jason knew, was an imbecilic exercise; there was no compelling reason for him to seek an answer. And yet his min… - Clifford D. Simak

When I talk of the purpose of life, I am thinking not only of human life, but of all life on Earth and of the life which must exist upon other planets throughout the universe. It is only of life on Earth, however, that one can speak with any certainty. It seems to me that all life on Earth, the sum total of life upon the Earth, has purpose. If the means were available, we could trace our ancestry — yours and mine — back to the first blob of life-like material that came into being on the planet. The same thing could be done for the spider that spun his web in the grass, and of the grass in which the web was spun, the bird sitting in the tree and the tree in which he sits, the toad waiting for the fly beneath the bush, and for the fly and bush. We are all genetic brothers. The chain of life, tracing back to that primordial day of life's beginning, is unbroken...

The red thought rose up inside Blaine’s brain: Why not kill him now?
For the killing would come easy. He was an easy man to hate. Not on principle alone, but personally, clear down to his guts.

Before Man goes to the stars he should learn how to live on Earth.