Why are cars called autos? It’s because they’re self–powered. In the Greek, the word autos means self. God has designed us with the capacity to make our own choices—we’re self-propelled, so to speak. Self is simply me, a personal being given the glorious gift of existence and awareness. But this gift of life has the effect of placing me at the center of my own personal universe. Sure, we deny that the world revolves around us. Yet given the true nature of self, it’s hard to believe otherwise!
The Bible uses the term heart to convey the idea of self. Think of the heart as the engine that runs our being. Both our mind-set and our behavior are dictated by what is in the heart. Jesus said, “The good man brings forth what is good out of his heart; but the evil man brings forth evil; for his mouth speaks from that which fills his heart.”
From Free from the Power of Sin: the Keys to Growing in God in Spite of Yourself