The mind cannot foresee its own advance.

Compared with the totality of knowledge which is continually utilized in the evolution of a dynamic civilization, the difference between the knowledge that the wisest and that which the most ignorant individual can deliberately employ is comparatively insignificant.

This is the constitutional limitation of man's knowledge and interests, the fact that he cannot know more than a tiny part of the whole of society and that therefore all that can enter into his motives are the immediate effects which his actions will have in the sphere he knows.

From the saintly and single-minded idealist to the fanatic is often but a step.

However human, envy is certainly not one of the sources of discontent that a free society can eliminate. It is probably one of the essential conditions for the preservation of such a society that we do not countenance envy, not sanction its demands by camouflaging it as social justice, but treat it, in the words of John Stuart Mill, as "the most anti-social and evil of all passions.

It may indeed prove to be far the most difficult and not the least important task for human reason rationally to comprehend its own limitations. It is essential for the growth of reason that as individuals we should bow to forces and obey principles which we cannot hope fully to understand, yet on which the advance and even the preservation of civilization depend.