It is now some fifty-two years since the first modern edition appeared of any part of Hephaistion of Thebes' compendium of astrology. The editor very properly collected in his introduction the scanty facts relative to the author and the unknown friend to whom he dedicates his work. But, apparently a little annoyed by the too positive assertion of Salmasius that all astrologers of that date were pagans, he put forth the hasty theory that this astrologer was a Christian. He had indeed no difficulty in proving that a somewhat unorthodox or lax Christian might have been a devotee of astrology at the time, about A.D. 381, when it is likely that Hephaistion wrote; but he went too far in the further statement that “das Werk des Hephaestion selbst bietet sicherlich keinen positiven Anhaltspunkt, dass der Verfasser desselben Nicht-Christ gewesen sei.” This has been echoed by later writers, as A. Bouché-Leclercq, who says “Il est possible qu'Hephestion de Thebes … fût chrétien,” and Fr. Boll, writing shortly before 1912, when a good deal more of our author had been printed in the C(orpus) C(odicum) A(strologicorum) G(raecorum). He sums up Engelbrecht's arguments, that the work begins σὺν θεῷ and is dedicated to one Athanasios, who is called ὁσιώτατος (and by other complimentary superlatives) and so may have been a Christian priest, concluding that the theory of the writer's Christianity is arrived at “wohl mit Recht.” As it seems to me remarkable that three learned men, of whom one had edited the astrologer and the others had certainly read him, should have overlooked the cogent evidence that he was a pagan, I think it worth while to set forth the proofs, positive and negative.