One of the foundational philosophical premises at the heart of Bahá'í ontology is that the structure of 'being' (wujÃºd) is one of 'process' and 'becoming' rather then static and fixed. This dynamic ontology in the writings of Bahá'u'lláh is typified by the symbolism of Fire which via its attribute `heat', is the cause of motion and hence the very foundation of being and existence. Fire, due to its dynamic nature, is often the symbol of the Primal Will (mashíyyat awalíyya) in the Bahá'í Writings, which manifests itself in history in the persons of the Manifestations of God. In one of Bahá'u'lláh's important tablets to Zoroastrians He states that this Divine Fire which is the Primal Will is the Cause of all things, that it is the secret contained in the Zoroastrian scriptures and that it is He who is the messianic appearance of this Celestial Fire (Ätar). In this paper the mystico-messianic hermeneutics of Bahá'u'lláh in which He enunciates to be the theophanic appearance of the Zoroastrian Divine Fire (Ätar) in person will be examined in light of some of the relevant material from the Gathas (the earliest Zoroastrian texts which are considered to be the Prophet's own words), and other Zoroastrian sources that point to this eschatological expectation. Also, some of the relevant history of the transference of this motif of the Zoroastrian Fire into early Greek philosophy, Judaism, Christianity, Arabic Hermetica/Alchemy and Islamicate philosophy will as well be briefly outlined.