Science has promised us truth...It has never promised us either peace or happiness.

The influence of the leaders is due in very small measure to the arguments they employ, but in a large degree to their prestige. The best proof of this is that, should they by any circumstance lose their prestige, their influence disappears.

Crowds are somewhat like the sphinx of ancient fable: It is necessary to arrive at a solution of the problems offered by their psychology or to resign ourselves to being devoured by them.

In crowds it is stupidity and not mother wit that is accumulated.

Are the worst enemies of society those who attack it or those who do not even give themselves the trouble of defending it?

The real cause of the great upheavals which precede changes of civilisations, such as the fall of the Roman Empire and the rise of the Arabian Empire, is a profound modification in the ideas of the peoples .... The memorable events of history are the visible effects of the invisible changes of human thought .... The present epoch is one of these critical moments in which the thought of mankind is undergoing a process of transformation.

One of the most constant characteristics of beliefs is their intolerance. The stronger the belief, the greater its intolerance. Men dominated by a certitude cannot tolerate those who do not accept it.