The three filters [against folly] operate through these particular questions: Literacy: What are the words? Numeracy: What are the numbers? Ecolacy: And then what?

Using the commons as a cesspool does not harm the general public under frontier conditions, because there is no public, the same behavior in a metropolis is unbearable.

A technical solution may be defined as one that requires a change only in the techniques of the natural sciences, demanding little or nothing in the way of change in human values or ideas of morality.

The greatest folly is to accept expert statements uncritically. At the very least, we should always seek another opinion.

You can never do merely one thing. The law applies to any action that changes something in a complex system. The point is that an action taken to alleviate a problem will trigger several effects, some of which may offset or even negate the one intended.

The optimum population is, then, less than the maximum.

Throughout history, human exploitation of the earth has produced this progression: colonize-destroy-move on.