While he lives, he must think; while he thinks, he must dream.

Intelligence is a valuable thing, but it is not usually the key to survival. Sheer fecundity ... usually counts. The intelligent gorilla doesn't do as well as the less intelligent but more-fecund rat, which doesn't do as well as the still-less-intelligent but still-more-fecund cockroach, which doesn't do as well as the minimally-intelligent but maximally-fecund bacterium.

It is change continuing change, inevitable change that is the dominant factor in society today.

Democracy cannot survive overpopulation. Human dignity cannot survive it. Convenience and decency cannot survive it. As you put more and more people into the world, the value of life not only declines, but it disappears. It doesn't matter if someone dies.

One thought that occurs to me is that men will continue to withdraw from nature in order to create an environment that will suit them better.

Knowledge is indivisible. When people grow wise in one direction, they are sure to make it easier for themselves to grow wise in other directions as well. On the other hand, when they split up knowledge, concentrate on their own field, and scorn and ignore other fields, they grow less wise - even in their own field.

I have never written a book that didn't teach me far more than it taught my reader.