In Chapter 3: "That Than Which Nothing Greater Can Be Thought": The Ineffable Mystery of God, Father Barron explores the concept and nature of God. He begins by relating Moses' encounter with God on Mount Sinai.
Father Barron explains only one of Thomas Aquinas' five arguments for the existence of God by considering the principle of contingency. Every thing in this world is "contingent" upon something else for its existence here. Every living thing and every inanimate thing begins and ends, it has a cause to start it and eventually an ending. "Such things do not contain within themselves the reason for their own existence. If they did, they would exist, simply and absolutely;they would not come and go...in regard to contingent things, we have to look outside of them, to an extrinsic cause, or set of causes, in order to explain their existence."