  Now, when Leibniz speaks in metaphysical rigor, he denies the underlying premise of Cartesian dualism: body is not a substance; so there can be no question of how it qua substance interacts with or is related to the mind, or thinking substance. Nevertheless, Leibniz was able to express his view for the vulgar – that is, for those expecting a Cartesian metaphysics – by saying that the mind and body can be said to form a union and interact insofar as the mind follows its laws, the body follows its laws, and they are in perfect harmony. The body and soul are not united to each other in the sense that Descartes had suggested, but the perceptions and appetitions of the soul will arise spontaneously from its own stores and will correspond to the actions of the body as well as to the events of the world. In other words, while the perceptions and appetitions of the mind or soul will be independent of the body, they will nevertheless correspond precisely to the actions of the particular body to which it is attached and be in perfect conformity with all the other substances of the world.