One advantage of exhibiting a hierarchy of systems in this way is that it gives us some idea of the present gaps in both theoretical and empirical knowledge. Adequate theoretical models extend up to about the fourth level, and not much beyond. Empirical knowledge is deficient at practically all levels.

Are we to regard the world of nature simply as a storehouse to be robbed for the immediate benefit of man?

Knowledge exists in minds, not in books. Before what has been found can be used by practitioners, someone must organize it, integrate it, extract the message.

Equilibrium is a figment of the human imagination.

Because of his capacity for abstract communications and language and his ability to enter in imagination into the lives of others, man is able to build organizations of a size and complexity far beyond those of the lower animals.

The controversy as to whether socialism is possible has been settled by the fact that it exists, and it is a fundamental axiom of my philosophy, at any rate, that anything that exists, is possible.

Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist.