 The soul is an intelligible entity but, as noted above, it is the intelligible entity that is directly engaged with the sensible realm. Intelligible entities are incorporeal and without extension and not present in bodies as in place. Following Plotinus, Porphyry distinguishes between the soul in itself, which seems to be identical the rational soul, and a second power of the rational, the lower soul, which is the soul in relation to the body and is alone directly engaged with it (Sent. 4). The lower soul is responsible for soul-functions that directly involve the body, such as sense-perception, desires, emotions and purely biological functions such as growth. In the tradition before Porphyry, this distinction sometimes became so sharp that it was supposed that each person has two distinct souls. Porphyry, by contrast, insists on the unity of the human soul: the lower functions are powers that depend on the rational soul (see Deuse 1983: 169–217). The distinction between the soul itself and its powers (the lower soul) is an instance of the distinction between internal and external acts, mentioned above. Thus, the soul itself has an intellectual activity that has the second powers or lower soul as its external act.