Augustine offers one of the pithiest definitions of sin: it is the state of being incurvatus in se (caved in on oneself). The powers of the soul, which are meant to orient us to nature and other human beings and the cosmos and finally the infinite mystery of God, are focussed in on the tiny and infinitely uninteresting ego. Like a black hole, the sinful soul draws all of the light and energy around it into itself.
Robert Barron