 This interaction happens in stages. Before the world has come into being, the universe was animated by the non-rational world soul, which accounts for the disordered motion of matter. In Plutarch's words, “what preceded the generation of the world was disorder, disorder not incorporeal or immobile or inanimate, but of corporeality amorphous and incoherent, and of motivity demented and irrational, and this was the discord of soul that has not reason” (De an. procr. 1014B; Cherniss' trans., altered). Plato speaks indeed of the receptacle as amorphous (Timaeus 50d7, 51a7), there is, however, no explicit mention of a non-rational pre-cosmic soul in the Timaeus, which is why Plutarch has been accused of arbitrariness in this regard (Cherniss, Plutarch Moralia, Loeb vol. XIII.1, 140–147). It is wrong, though, to treat Plutarch as one might treat a modern commentator of the Timaeus, with conscientious scholarly attention to what is and is not made explicit in a text.  Plutarch assumes that there is a single “Platonic view” about the generation of the world, the first principles of reality, and the role of soul in the world's generation, and he seeks support for his interpretation in many Platonic dialogues. He identifies the non-rational soul with the “disorderly and maleficent soul” of Laws X (a testimony Plutarch himself considers unambiguous, De Iside 370F), with the “limitlessness” of the Philebus (26b), the “congenital desire” and “inbred character” of the Politicus (272d, 273b), and with the necessity (anankê) and the generation (genesis) of Timaeus 52d (De an. procr. 1014D-1015A). None of these passages lend clear support to Plutarch's interpretation, since nowhere does Plato explicitly speak of a pre-cosmic maleficent soul or other pre-cosmic soul-like entities: even the maleficent soul of the Laws is not pre-cosmic (Cherniss, ibid. 140). Yet Plutarch's interpretation does have merits in imposing consistency on Plato's work as a whole in the following sense. First, according to the Timaeus (35a) the demiurge (the creator god) does not create the substance of the soul, but compounds the world soul by blending indivisible with divisible being, which Plutarch not unreasonably identifies with the divine intellect and the non-rational world soul respectively (De an. procr. 1014D-E).  This does justice to the nature of the soul, which for Platonists is not subject to change and corruption. Secondly, it was generally assumed that no motion is possible without a principle of motion (cf. Aristotle, De anima 402a6–7), and this traditionally is identified with the soul in Platonism (cf.  Phaedrus 245c-e); so the disordered motion of matter before the creation of cosmos that Plato appears to postulate in the Timaeus needs to be accounted for by a soul (see Laws 892a), which must, then, be a pre-cosmic one (De an. procr.  1015E).