 Scotus agrees with Thomas Aquinas that all our knowledge of God starts from creatures, and that as a result we can only prove the existence and nature of God by what the medievals call an argument quia (reasoning from effect to cause), not by an argument propter quid (reasoning from essence to characteristic). Aquinas and Scotus further agree that, for that same reason, we cannot know the essence of God in this life. The main difference between the two authors is that Scotus believes we can apply certain predicates univocally—with exactly the same meaning—to God and creatures, whereas Aquinas insists that this is impossible, and that we can only use analogical predication, in which a word as applied to God has a meaning different from, although related to, the meaning of that same word as applied to creatures. (See  medieval theories of analogy  for details.)