  Proclus’ epistemology is firmly rooted in his theory of the soul. For Proclus, souls as self-moving principles represent the lowest level of entities that are capable of reverting upon itself (so called self-constituted beings [authypostata], see Elem. Theol. § 40–51). They are incorporeal, separable from bodies and indestructible/immortal (Elem. Theol. § 186–7). Yet, they are principles of life and of movement of bodies (Elem. Theol. § 188). In accordance with Proclus’ general metaphysical principles (cf. above 3.1), from the unparticipated soul-monad proceed different kinds of participated soul: divine souls, daemonic souls, human souls, souls of animals). As with other Platonists, Proclus frequently discusses the vexed question as to why a soul would descend into a body at all (‘fall of the soul’) (see Dörrie / Baltes (2002.2) 163–218). Moreover, the Neoplatonist distinguishes between altogether three so-called vehicles (ochêmata) of the soul. The rational soul is permanently housed in the luminous vehicle, while the non-rational soul is located in the pneumatic vehicle. By being incarnated in a human body, soul, or rather, the vegetative soul attains thus a (third) ‘shell-like’ vehicle. The theory of the different vehicles or the psychic ‘astral body,’ familiar nowadays from modern theosophic theories, fulfils several crucial functions in Neoplatonic psychology: it explains (a) how an incorporeal soul can be linked to a body, (b) how souls can move in space, (c) how souls can be punished after death (cf. Plato’s myths), (d) where certain faculties of the soul such as imagination are located. Proclus distinguishes between two kinds of vehicles, one mortal and the other immortal (In Tim. III 236.31 ff. and Elem. Theol. § 207–210). Proclus also adheres to the Platonic theory of transmigration, but argues that human souls never enter animal bodies as their constitutive forms. For only animal souls can be organizing principles of animal bodies. If some rational souls are ‘degraded’ in the next life and forced to live in an animal body because of their misdemeanour in this life, they are only ‘relationally’ (schesei) present to this animal body.