We must protect the right of our opponents to speak because we must hear what they have to say.

The time has come to stop beating our heads against stone walls under the illusion that we have been appointed policeman to the human race.

Ignore what a man desires and you ignore the very source of his power.

The only feeling that anyone can have about an event he does not experience is the feeling aroused by his mental image of that event ... For it is clear enough that under certain conditions men respond as powerfully to fictions as they do to realities.

The genius of a good leader is to leave behind him a situation which common sense, without the grace of genius, can deal with successfully.

The public must be put in its place, so that it may exercise its own powers, but no less and perhaps even more, so that each of us may live free of the trampling and the roar of a bewildered herd.

The radical novelty of modern science lies precisely in the rejection of the belief... that the forces which move the stars and atoms are contingent upon the preferences of the human heart.