The social sciences, like much of biology but unlike most fields of the physical sciences, have to deal with structures of essential complexity, i.e. with structures whose characteristic properties can be exhibited only by models made up of relatively large numbers of variables.

In no other field has the world yet paid so dearly for the abandonment of nineteenth-century liberalism as in the field where the retreat began: in international relations. Yet only a small part of the lesson which experience ought to have taught us has been learned.

The Germans would appear as the disturbers of peace, as they already do to some people, merely because they were the first to take the path along which all the others were ultimately to follow.

Socialism has never and nowhere been at first a working-class movement. It is by no means an obvious remedy for the obvious evil which the interests of that class will necessarily demand. It is a construction of theorists.

The mind cannot foresee its own advance.

There may be few instances in which the superstition that only measurable magnitudes can be important has done positive harm in the economic field: but the present inflation and employment problems are a very serious one.

One need not be a prophet to be aware of impending dangers. An accidental combination of experience and interest will often reveal events to one man under aspects which few yet see.