No progress, either moral or material, can be made in a world which is frozen, like ours, into a rigid mold of suppression of liberties. - Damon Knight

When two alien cultures meet, the stronger must transform the weaker with love or hate.

He was going to die. His mind flinched back in horror from that, but it was still there, grinning, implacable. His body would rot under the ground, while delicious things were still happening in the sunlight.

Voluntary birth control methods only work on the people who choose to use ’em. A population check that doesn’t work on everybody doesn’t work at all, because it simply breeds out the ones who use it. The only population check that really works is one that affects everybody, like a limit of space or food.