Gessius of Petra (Greek: Γέσιος, Gesios)[1] was an Arab physician, iatrosophist and pagan philosopher active in Alexandria in the late 5th and early 6th century.
Stephanus of Byzantium, on the other hand, writes that he came from the agricultural region of el-Ji (today Wadi Musa) not far from Petra.
[5] According to Sophronius of Jerusalem, Gessius received baptism into Christianity under imperial pressure but remained a pagan in secret.
[2][5] Since Zacharias in his Ammonius and Damascius in his Life of Isidore both treat Gessius as nothing other than pagan, this conversion, if it took place, must have happened after the writing of these works.
[2] According to Sophronius, Gessius, rising from the baptismal waters, said "this is a bath which takes one's breath away", a mocking paraphrase of a line from the Odyssey and a clear indication of continuing pagan sympathies.
[2][5] Edward Watts argues that this story is a literary invention of Sophronius,[2] but Barry Baldwin considers it plausible.