 A coloured body, if we speak accurately, is the same absurdity with a square sound. We need no experience to prove that heat, cold, colours, tastes, etc. are not real qualities of bodies; because the idea of matter and of these qualities are incompatible. But is there indeed any such incompatibility between actions and right? Or any such absurdity in affirming the one of the other? Are the ideas of them as different as the idea of a sensation and its cause? (R 46)