One can readily understand the Greek rationale for linking Hermes with Thoth. Both gods were messenger divinities and both personae dramatis had a close affinity with the moon and realm of the dead. Moreover, devotees of Thoth were convinced that Trismegistus originated the Hermetic doctrines. For purposes of this study, at any rate, one vital consideration is that elysian “Hermes” uses symbolic terms such as Father, Son or Grandson, which correspond to God, the cosmos and humanity. Trismegistus believes God the Creator is “the supreme Father” in that he produced the universe and its metaphysical trappings. Invoking euhemerism once again, Lactantius explains the socio-religious developments of Hermetic veneration:
And although he [Hermes] was a man, yet he was of great antiquity, and most fully imbued with every kind of learning, so that the knowledge of many subjects and arts acquired for him the name of Trismegistus. He wrote books, and those in great numbers, relating to the knowledge of divine things, in which he asserts the majesty of the supreme and only God, and makes mention of Him by the same names which we do, ‘lord and father.' 
Lactantius was not the first writer to posit a terrestrial origin for the Olympian messenger Hermes. Cicero suggested there were at least five mundane individuals who claimed to possess the moniker Hermes. In this way, De natura Deorum illustrates the tendency some Greeks exhibited to conceptually dissociate Trismegistus from Hermes (Thoth). Nevertheless, the accretion concerning a god establishing the Egyptian city of Hermopolis ostensibly commenced with Lactantius; he was its originator.