 and conversely where there is simplicity there cannot be extension or figure or divisibility (§§1–3). Yet monads must have some qualities in order to exist (§8) and to differ from one another, as they must (§9), and if the fundamental properties of matter are excluded, this leaves the fundamental properties of mind, which Leibniz holds to be perception, “The passing state which enfolds and represents a multitude in unity” (§14) and appetition, “the internal principle which brings about change or the passage from one perception to another” (§15; all from PPL: 643–4). This argument clearly seems to imply that all finite substances are ultimately mental in nature (and the infinite substance, God, is obviously mental in nature), thus it seems to be a paradigmatic ontological argument for idealism, from which an epistemological argument for idealism would automatically follow, since if there is knowledge of reality at all, which Leibniz hardly seems to doubt, and reality is ultimately mental, then knowledge too must be of the mental.