 According to Averroes the existence of Nature is self-evident as well as its definition; the metaphysician does not have to prove it. He disagrees with Avicenna who seemingly contended that Nature belongs to the class of things that are not self-evident and that the definition above is not known by itself; for this reason the metaphysician should have to explain what Nature is. Averroes is not sure about what Avicenna said and he admits that the metaphysician is qualified to refute those views denying the existence of Nature as a principle. He guesses that Avicenna was moved to this view 