John Dillon, in his monograph “The Roots of Platonism”, put forward the thesis that the doctrine of Ideas as God’s thoughts had already appeared in the Old Academy and was continuously present in the Platonic tradition preceding the emergence of Middle Platonism. However, so far researchers have assumed that the first thinker who explicitly identified Ideas with God’s thoughts was a Jewish thinker, Philo of Alexandria. Dillon supported his argumentation on very uncertain and unclear sources, which are some of the statements contained in fragments of Speusippus, Xenocrates, and Antiochus of Ascalon. According to the Irish researcher, Philo was familiar with this philosophical tradition, and therefore his doctrine of the Logos of God, in which the world of Ideas is located, is by no means original. In this paper, Mrugalski aims to prove that the Jewish thinker of Alexandria was able to build his doctrine of Ideas as God’s thoughts himself. In fact, this concept arises within the allegorical commentary on the Pentateuch, which, on the one hand, uses numerous philosophical concepts and, on the other, continues to be a biblical commentary. Meanwhile, biblical theology hypostatized divine attributes such as the wisdom of God or the Logos long before Philo and assigned them eternity and creative power. It is true that the thinker of Alexandria knew and even quoted the works of Plato, Aristotle, or the Stoics. Sometimes he also argued with their concepts. Yet we are not sure whether Philo knew the fragments of the philosophers of the Old Academy to which Dillon refers. Moreover, we are not sure whether the doctrine of Ideas as God’s thoughts appears in these fragments at all. However, we have access to the biblical texts on which Philo commented, and we can trace the argumentation within which he came to the conclusion that God is an intellect that eternally thinks and by thinking creates the world, first the intelligible one and then the perceptible one.