Gustave Flaubert, the keen observer of human nature, looked at the hidden motives that lead people to act in accordance with their nature.
This passage from The Letters of Gustave Flaubert is worth reflecting on.
From the idiot who wouldn’t give a sou to redeem the human race, to the man who dives beneath the ice to rescue a stranger, do we not all seek, according to our various instincts, to satisfy our natures? Saint Vincent de Paul obeyed an appetite for charity, Caligula an appetite for cruelty. Everyone takes his enjoyment in his own way and for himself alone. Some direct all activity toward themselves, making themselves the cause, the center, the end of everything; others invite the whole world to the banquet of their souls. That is the difference between prodigals and misers: the first take their pleasure in giving, the second in keeping.
Commenting on this passage in Happiness: A Philosopher's Guide, Frederic Lenoir believes it “describes the core of egotism that underlies the pursuit of our aspirations and the realization of our actions.”