All life is fired by longing. The simplest of plants and the highest of human love have this in common — yearning, restlessness, a certain insatiable pressure to eat, to grow, to breed, to push beyond self. Yet longing is something that is rarely examined, despite the fact that it lies at the very heart of the soul. What is longing? What does it mean to yearn? What is this insatiable press inside of us to eat, to drink, to make love, to want to be outside our own skins and to want to make ourselves immortal? Mostly it is unconscious, a dark relentless pressure to reach beyond ourselves.
— Ronald Rolheiser, Against an Infinite Horizon: The Finger of God in Our Everyday Lives