This volume of Proclus’ commentary on Plato’s Timaeus records Proclus’ exegesis of Timaeus 27a-31b, in which Plato first discusses preliminary matters that precede his account of the creation of the universe, and then moves to the account of the creation of the universe as a totality. For Proclus this text is a grand opportunity to reflect on the nature of causation as it relates to the physical reality of our cosmos. The commentary deals with many subjects that have been of central interest to philosophers from Plato’s time onwards, such as the question whether the cosmos was created in time, and the nature of evil as it relates to physical reality and its ontological imperfection.