In the patristic exegesis of the first three centuries AD, the Old Testament theophanies were usually considered as an argument for the pre-existence of the Logos, as well as for his Divine origin. Furthermore, according to Greek and Latin apologists, the phrase ‘I am who I am’ (Exod. 3:14) from the story of God’s revelation on Mount Horeb was pronounced, not by the Father, but by the Son who was always working with the Father. The theologians of the Alexandrian tradition interpreted Exod. 3:14 in a slightly different way. Their attention was mainly attracted by the verb ‘to be’, or, more precisely, by the designation of God as ‘being’ (ὁ ὤν), since such a participle form appears in the Greek translation of the Septuagint. According to Philo, Clement and Origen of Alexandria, it is only God who is a true being, because, unlike other beings, He is eternal and immutable in His existence. On the other hand, the Alexandrian thinkers also claimed that the term ‘being’ (τὸ ὄν) could not be a proper name of God. As the Divine essence is transcendent and infinite, it cannot be embraced by any definition or name. The God of the Alexandrians, therefore, remains unknowable and unnameable. Although in Alexandrian exegesis apophatics takes precedence over the ontologisation of the name of God, the allegorical interpretation of the Scriptures proposed by Philo, Clement and Origen retains its philosophical character. In fact, in its background it appeals to numerous philosophical concepts, and especially to the Platonic and Middle Platonic theory of participation and the doctrine of the primary and supreme Principles.