Knowledge is boundless,--human capacity, limited.
Wicked people sometimes perform good actions. I suppose they wish to see if this gives as great a feeling of pleasure as the virtuous claim for it.
Egotism is the tongue of vanity.
Success makes success, like money makes money.
Contact with the world either breaks or hardens the heart.
It's a question of prudence. Nobody has a high opinion of fishwives but who would dare offend them while walking through the fish market.