  Proclus argues at length that the human soul has to contain innate knowledge. Therefore, one should not consider it an empty writing tablet, as Aristotle does (Aristotle, De anima III 4). He is wrong in asserting that the soul contains all things potentially. According to Proclus, the soul contains all things (i.e., all logoi) in actuality, though due to the ‘shock of birth’ it may seem as if the soul has fallen to potentiality. At In Crat. § 61, Proclus asserts that the soul does not resemble an empty writing tablet (agraphon grammateion) and does not possess all things in potentiality, but in act. In Eucl. 16.8–13 expresses the same idea: “the soul is not a writing tablet void of logoi, but it is always written upon and always writing itself and being written on by the intellect.” As with his philosophy of mathematics, Proclus presents a detailed criticism of the view that universal concepts are derived from sensible objects (by abstraction, induction, or collection). In the fourth book of his Commentary on Plato’s Parmenides and in the two prologues of the Commentary on Euclid we find the most comprehensive criticism of abstractionism in antiquity (see Helmig (2010) and (2012) 205–221).