80. Des Cartes perceived that souls communicate no force to bodies, because the quantity of force in matter is always the same. Nevertheless, he believed that souls might change the direction of bodies. But this was because the world was at that time ignorant of the law of nature, which requires the conservation of the same total direction in matter. Had he known this, he would have hit upon my system of preëstablished harmony. 81. According to this system, bodies act as if there were no souls, and souls act as if there were no bodies; and yet both act as though the one influenced the other. 82. As to spirits, or rational souls, although I find that at bottom the same principle which I have stated—namely, that animals and souls begin with the world and end only with the world—holds with regard to all animals and living things, yet there is this peculiarity in rational animals, that although their spermatic animalcules, as such, have only ordinary or sensitive souls, yet as soon as those of them which are _elected_, so to speak, arrive by the act of conception at human nature, their sensitive souls are elevated to the rank of reason and to the prerogative of spirits. 83. Among other differences which distinguish spirits from ordinary souls, some of which have already been indicated, there is also this: that souls in general are living mirrors, or images of the universe of creatures, but spirits are, furthermore, images of Divinity itself, or of the Author of Nature, capable of cognizing the system of the universe, and of imitating something of it by architectonic experiments, each spirit being, as it were, a little divinity in its own department. 84. Hence spirits are able to enter into a kind of fellowship with God. In their view he is not merely what an inventor is to his machine (as God is in relation to other creatures), but also what a prince is to his subjects, and even what a father is to his children. 85. Whence it is easy to conclude that the assembly of all spirits must constitute the City of God—that is to say, the most perfect state possible, under the most perfect of monarchs. 86. This City of God, this truly universal monarchy, is a moral world within the natural; and it is the most exalted and the most divine among the works of God. It is in this that the glory of God most truly consists, which glory would be wanting if his greatness and his goodness were not recognized and admired by spirits. It is in relation to this Divine City that he possesses, properly speaking, the attribute of _goodness_, whereas his wisdom and his power are everywhere manifest.