287. [263] Concerning the simple substance Leibnitz said, that his opinion concerning the monad was never like that of Wolff concerning the simple substance. He said that he indeed acknowledged monads as unities but that there were in them simpler and purer substances by which the monad was formed, from which changes of state existed therein; since if there were nothing therein, it would be nothing, in which there cannot be any change of state, for a vacuum admits of no change. Leibnitz therefore wondered that Wolff held that his monad, which he calls a simple substance, was created out of nothing, and that when divided it falls into nothing; and yet he had attributed changes of state to it; and also that he had called some existences simple substances, and which are in nature, which anyone can see are aggregations of substances, like the parts of the air and ether, the elements of metals, and also souls. Wolff said that he wished by his definitions of his simple substances to captivate the minds of theologians, who want it to be believed that all things have been created by God out of nothing, immediately; at that time not knowing that his followers, by confirming these principles in themselves, would close in themselves the ways to angelic wisdom, which nevertheless are founded on natural truths.