The scenes of universe are continuously shifting, and one objet follows another in uninterrupted succession; but the power of force, which actuates the whole machine, is entirely concealed from us, and never discovers itself in any of sensible qualities of body. We know that, in fact, heat is constant attendant of flame; but what is the connexion between them, we have no room so much as to conjecture or imagine. It is impossible, therefore that the idea of power can be derived from contemplation of bodies, in single instances of their operations; because no bodies ever discover any power, which can be original of this idea.