Hadrian's philhellenism may have been one reason for his adoption, like Nero before him, of the beard as suited to Roman imperial dignity; Dio of Prusa had equated the growth of the beard with the Hellenic ethos. Hadrian's beard may also have served to conceal his natural facial blemishes. All emperors before him (except Nero) had been clean-shaven; emperors who came after him until Constantine the Great were bearded and this imperial fashion was revived again by Phocas at the beginning of the 7th century.