To complete the present discussion, however, it is enough to notice that intelligence and will must be found in every creature, and that thus we account for the "appetition" and the "perception" that characterize even the lowest monad. The scale of monads, however, would not be as complete as possible unless there were beings in whom appetition became volition, and perception, self-conscious intelligence. Such monads will stand in quite other relation to God than the blind impulse-governed substances. "Spirits," says Leibniz, "are capable of entering into community with God, and God is related to them not only as an inventor to his machine (as he is to other creatures) but as a prince to his subjects, or, better, as a father to his children. This society of spirits constitutes the city of God,--the most perfect state under the most perfect monarch. This city of God, this truly cosmopolitan monarchy, is a moral world within the natural. Among all the works of God it is the most sublime and divine. In it consists the true glory of God, for there would be no glory of God unless his greatness and goodness were known and admired by spirits; and in his relation to this society, God for the first time reveals his goodness, while he manifests everywhere his power and wisdom. And as previously we demonstrated a perfect harmony between the two realms of nature,--those of efficient and final causes,--so must we here declare harmony between the physical realm of nature and the moral realm of grace,--that is, between God as the architect of the mechanical world-structure, and God as the monarch of the world of spirits." God fulfils his creation, in other words, in a realm of spirits, and fulfils it because here there are beings who do not merely reflect him but who enter into relations of companionship with him, forming a community. This community of spirits with one another and with God is the moral world, and we are thus brought again to the ethics of Leibniz. It has been frequently pointed out that Leibniz was the first to give ethics the form which it has since kept in German philosophy,--the division into _Natur-recht_ and _Natur-moral_. These terms are difficult to give in English, but the latter corresponds to what is ordinarily called "moral philosophy," while the former is political philosophy so far as that has an ethical bearing. Or the latter may be said to treat of the moral ideal and of the moral motive and of duty in themselves, while the former deals with the social, the public, and in a certain sense the external, aspects of morality.