 This proof that God—an infinite, eternal (necessary and self-caused), indivisible being—is the only substance of the universe proceeds in three simple steps. First, establish that no two substances can share an attribute or essence (Ip5). Then, prove that there is a substance with infinite attributes (i.e., God) (Ip11). It follows, in conclusion, that the existence of that infinite substance precludes the existence of any other substance. For if there were to be a second substance, it would have to have some attribute or essence. But since God has all possible attributes, then the attribute to be possessed by this second substance would be one of the attributes already possessed by God. But it has already been established that no two substances can have the same attribute. Therefore, there can be, besides God, no such second substance.