1 Corinthians 11:14

Doth not even nature itself teach you This argument from nature must not be pressed too far. St Paul is speaking of the natural sense of what is fitting in those whom he addressed. In early times the Greeks and the Romans wore long hair, and the Gauls and Germans did so in St Paul's own time. So Homer continually speaks of the "long-haired Greeks." St Chrysostom remarks that those who addicted themselves to philosophy in his day wore their hair long. But this was mere affectation. Cf. Horace, De Arte Poetica, 297,

"Bona pars non ungues ponere curat,

Non barbam, secreta petit loca, balnea vitat."

But the general verdict of society has been that appealed to by the Apostle. "This instinctive consciousness of propriety on this point had been established by custom, and had become φύσις (nature)." Meyer.