It may be added that Leibniz's æsthetic theory, so far as developed, rests upon the same basis as his ethical,--namely, upon membership in the "city of God," or community of spiritual beings. This is implied, indeed, in a passage already quoted, where he states the close connection of beauty with harmony and perfection. The feeling of beauty is the recognition in feeling of an order, proportion, and harmony which are not yet intellectually descried. Leibniz illustrates by music, the dance, and architecture. This feeling of the harmonious also becomes an impulse to produce. As perception of beauty may be regarded as unexplained, or confused, perception of truth, so creation of beauty may be considered as undeveloped will. It is action on its way to perfect freedom, for freedom is simply activity with explicit recognition of harmony. We cannot do better than quote the conclusion of the matter from Leibniz's "Principles of Nature and of Grace," although, in part, it repeats what we have already learned. "There is something more in the rational soul, or spirit, than there is in the monad or even in the simple soul. Spirit is not only a mirror of the universe of creatures, but is also an image of the divine being. Spirit not only has a perception of the works of God, but is also capable of producing something which resembles them, though on a small scale. To say nothing of dreams, in which we invent without trouble and without volition things upon which we must reflect a long time in order to discover in our waking state,--to say nothing of this, our soul is architectonic in voluntary actions; and, in discovering the sciences in accordance with which God has regulated all things (_pondere_, _mensura_, _numero_), it imitates in its department and in its own world of activity that which God does in the macrocosm. This is the reason why spirits, entering through reason and eternal truths into a kind of society with God, are members of the city of God,--that is, of the most perfect state, formed and governed by the best of monarchs, in which there is no crime without punishment, and no good action without reward, and where there is as much of virtue and of happiness as may possibly exist. And this occurs not through a disturbance of nature, as if God's dealing with souls were in violation of mechanical laws, but by the very order of natural things, on account of the eternal, pre-established harmony between the kingdoms of nature and grace, between God as monarch and God as architect, since nature leads up to grace, and grace makes nature perfect in making use of it."