He’d seen too often how little of the universe is designed for man to neglect any safety measure. - Poul Anderson

The end of the world—was the sky going to open up, would the angels pour down the vials of wrath on a shaking land, and would God appear to judge the sons of men? He listened for the noise of great galloping hoofs, but there was only the wind in the trees.
That was the worst of it. The sky didn’t care. The Earth went on turning through an endlessness of dark and silence, and what happened in the thin scum seething over its crust didn’t matter.

We do need something to lift us out of ourselves. It's wrong to carry our pettinesses along to the stars."
"We will, though," he said. "We can't help it. How do you escape being what you are?

As evil waxes, the very men who stand for good will in their fear use ever worse means o’ fighting, and thereby give evil a free beachhead.