No one should be able to enter a wilderness by mechanical means.

A finite world can support only a finite population; therefore, population growth must eventually equal zero.

An attack on values is inevitably seen as an act of subversion.

Every plausible policy must be followed by the question 'And then what?'

It takes five years for a willing person's mind to change. Have patience with yourself and others when treading in an area protected by a taboo.

In an approximate way, the logic of commons has been understood for a long time, perhaps since the discovery of agriculture or the invention of private property in real estate.

The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them.