 The determination of the soul’s nature and essence sets out from the definition of the soul given in empirical psychology as that in us which is conscious of itself and other things. Wolff argues that this consciousness is the result of a complex activity that involves reflection on and comparison of parts of a given perception as well as attention and memory (RP: §§22–3, 25). Given this, Wolff contends, the soul must be distinct from body since such an act cannot be explained in terms of a change in figure, magnitude, or the location of parts, through which alone changes in body are possible. Similar considerations serve to show that no composite can think, and thus that the soul, as conscious, must not be composite and is therefore simple, and indeed, a simple substance, since it perdures through changes in its thoughts (RP: §§44, 47–8). That the soul is a substance further implies for Wolff (as it did for Leibniz) that it is endowed with a power, understood as a sufficient reason for the actuality of the states that are possible for it through its faculties (RP: §§54–5; cf. Blackwell 1961, Heßbrüggen-Walter 2004). Wolff proceeds to determine the character of this power (which must be a single one given the soul’s simplicity), and he concludes that, because sensations are representations of the world in accordance with the position of the organic body, and because all of the representations the soul is capable of are derived from sensations, it follows that the soul’s power is just a power of representing the world in accordance with the position of the body, which power Wolff finally identifies as the essence and nature of the soul (RP: §§64–9).