I discovered when I had a child of my own that I had become a biased observer of small children. Instead of looking at them with affectionate but nonpartisan eyes, I saw each of them as older or younger, bigger or smaller, more or less graceful, intelligent, or skilled than my own child.

I had my father's mind, but he had his mother's mind. Fortunately, his mother lived with us and so I early realized that intellectual abilities of the kind I shared with my father and grandmother were not sex-linked.

I think rigid heterosexuality is a perversion of nature.

Humanity . . . lies in man's capacity to question the known and imagine the unknown.

Parents feel like immigrants in the country of the young.

No society has ever yet been able to handle the temptations of technology to mastery, to waste, to exuberance, to exploration and exploitation... We have to learn to cherish this earth and cherish it as something that's fragile, that's only one, it's all we have... We have to use our scientific knowledge to correct the dangers that have come from science and technology.

For the human species to evolve, the conversation must deepen.