Will Durant spent his whole life worrying that he was a failure. He wrote 13 volumes of The Story of Civilization over 50 years, a project so vast it seems almost incomprehensible. And he was worried he was a failure.
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The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents. We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far.
Howard Phillips Lovecraft — The Call of Cthulhu
The universe is not required to be in perfect harmony with human ambition.
Carl Sagan — Broca's Brain: Reflections on the Romance of Science
It is not enough to be busy; so are the ants. The question is: what are we busy about?
Henry David Thoreau — Letter to H.G.O. Blake