Three hundred years after its appearance Christianity was the recognized state religion in the Roman World Empire, and in barely sixty years socialism has won itself a position which makes its victory absolutely certain.

All that is real in human history becomes irrational in the process of time.

Bare-faced covetousness was the moving spirit of civilization from its first dawn to the present day; wealth, and again wealth, and for the third time wealth; wealth, not of society, but of the puny individual, was its only and final aim.

All history has been a history of class struggles, of struggles between exploited and exploiting, between dominated and dominating classes at various stages of social development.

In science, each new point of view calls forth a revolution in nomenclature.

People have learned by bitter experience that the "European fraternal union of peoples" cannot be achieved by mere phrases and pious wishes, but only by profound revolutions and bloody struggles; they have learned that the question is not that of a fraternal union of all European peoples under a single republican flag, but of an alliance of the revolutionary peoples against the counter-revolutionary peoples, an alliance which comes into being not on paper, but only on the battlefield.

One day we shall certainly 'reduce' thought experimentally to molecular and chemical motions in the brain; but does that exhaust the essence of thought?