  This discussion of Du Châtelet's understanding of the (hypothetically)  necessary metaphysical constitution of the world further underscores a point about her first principles of knowledge mentioned above. While the fundamental metaphysical truth that only unextended beings can serve as the simple beings of the created world—simple beings out of which complex beings are made—may be repugnant to sense and imagination, reason (as captured by her PC in this case) demands we believe it (IP §135). But this indicates that Du  Châtelet—like Wolff—may start with a psychological conception of the PC, but (again like Wolff), she takes this psychological conception of the principle to indicate that there are underlying logical and ontological truths which are the source of our psychological response to contradictions. So one of Du Châtelet's first principles, in this case, gives us knowledge of metaphysical essences. Importantly, Du Châtelet takes her conclusion that substances must be simple in the way just characterized to be necessarily true on the hypothesis that God chooses to actualize our world.