Eusebius is first mentioned by Gregory of Nazianzus (Ep. 19.2; 42.2), who also refers to him twice periphrastically as “a man remarkable for piety,” and “(he) who bore the name of piety” (Greg. Naz. Or. 43.28.3–4; 37.2–3, where the keyword is eusebeia).

According to the Gregory, who is our main source on him, Eusebius was one of the “most renowned” citizens of Caesarea (Caesarea in Cappadocia). More exactly, he was “one of the first in town” (Greg. Naz. Or. 18.33; PG 35.1028.B14; C7), that is (possibly) a principalis, a leading member in t…