The philosophical usage and the proper noun derive from Plato's Timaeus, written c. 360 BC, in which the demiurge is presented as the creator of the universe. This is also the definition of the demiurge in the Platonic (c. 310–90 BC) and Middle Platonic (c. 90 BC – AD 300) philosophical traditions. In the various branches of the Neoplatonic school (third century onwards), the demiurge is the fashioner of the real, perceptible world after the model of the Ideas, but (in most Neoplatonic systems) is still not itself "the One".