Superficial knowledge ... is hurtful to those who possess true genius; for it necessarily draws them away from their main object, wastes their industry over details and subjects foreign to their needs and natural talent, and lastly does not serve, as they flatter themselves, to prove the breadth of their mind. In all ages there have been men of very moderate intelligence who knew much, and so on the contrary, men of the highest intelligence who knew very little. Ignorance is not lack of intelligence, nor knowledge a proof of genius.

Our errors and our controversies, in the sphere of morality, arise sometimes from looking on men as though they could be altogether bad, or altogether good.

As soon as an opinion becomes common it is sufficient reason for men to abandon it and to uphold the opposite opinion until that in its turn grows old, and they require to distinguish themselves by other things. Thus if they attain their goal in some art or science, we must expect them soon to cast it aside to acquire some fresh fame, and this is partly the reason why the most splendid ages degenerate so quickly, and, scarcely emerged from barbarism, plunge into it again.

Great men undertake great things because they are great; fools, because they think them easy.

Sometimes a lengthened period of prosperity melts away in a moment; just as the heat of summer flies before a day of tempest.

Lazy people always intend to start doing something.

The heaviest object in the world is the body of the woman you have ceased to love.