“Sincerity cannot come together in a heart with the love of praise and craving for what people have, any more than water and fire, or the desert lizard and the fish.”

Ibn al-Qayyim follows this with instructions: when your self asks you for sincerity, first go to greed and slaughter it with the knife of despair — of expecting nothing from people — then go to praise and renounce it as the lovers of this world renounce the next. Do that, he says, and sincerity becomes easy. The desert lizard and the fish never meet because neither can live where the other does.