The only property that follows from the union of mind and body — and cannot proceed from either alone — is their mutual acting upon each other.

Le Grand described the mind-body union in terms directly borrowed from Descartes. However, Le Grand attempted to explicate further than did Descartes the nature of the mind-body union. According to Le Grand, there are three kinds of union, each possessing its own principle which effects that union: the first is that of two minds whose principle of union is love; the second is that of two physical bodies whose principle of union is local presence; and the third is that of the mind and body whose