 It is easy to see why this is one of the better-known passages in the Monadologie. It contains a vivid imaginative thought experiment that is presented in support of an anti-materialist conclusion, namely that perception is inexplicable by means of shapes and motions. Given that thought experiments along these lines have been popular in contemporary philosophy of mind it might seem natural to suppose that Leibniz takes the thought experiment to provide a conclusive argument for his conclusion (it is sometimes referred to as “Leibniz’s Mill Argument”). Although this is not the place to discuss the issue at length, we can say that Leibniz’s remarks on the exoteric/esoteric distinction suggest that this might not be the case. It is plausible to think that the passage is designed to appeal to people who rely heavily on the imagination in doing philosophy; it could be a heuristic that will help motivate Leibniz’s thesis that perception is a property of simple substances and not of bodies, not a rigorous argument for this conclusion .