In this article, we focus on Proclus' commentary on Plato's Timaeus about how the divine Demiurge intervenes in matter. It is an interesting extract due to the fact that Proclus manages to combine philosophical perspective with theological interpretation and scientific analysis. In the six chapters of the article, we present the theory on dualism established by the representatives of Middle Platonism, we approach the question of the production of the corporeal hypostases, we examine limit and unlimited as productive powers, we (...) explain production in the sense of co-production as well as why matter without qualities is excluded from the entire procedure, and we discuss the principle of the supremacy of the supreme Principle. The most important conclusion drawn according to Proclus, who adopts moderate skepticism, is that, although in his early dialogues Plato tends to dualism, he does this for methodological purposes, for Plato's views are actually connected with ontological monism. (shrink)