Here the reader is provided with a reconstruction of the nature of the Chaldean First Principle. This is shown to be a paternal monad (called ‘The Father’ by the Oracles) that manifests itself in the primordial triad Father – Power – Intellect. The Chaldean First Principle exists then both above the first triad and within it as its first member. This reconstruction is based on Proclus’ exegesis of the Chaldean oracular fragments 4 and 5 des Places as well as on Damascius’ exegesis of the Oracles, which provides us with information that fills in the gaps left open by Proclus’ oracular exegesis. In this chapter, it will be shown how the Chaldean Principle is influenced not only by coeval Platonism but also by the Heraclitean-Stoic conception of the First Principle as primordial fire.