
“If you are at Rome, live in the Roman style; if you are elsewhere, live as they live there.”
Si fueris Romae, Romano vivito more;
Si fueris alibi, vivito sicut ibi.
Quoted in Ductor Dubitantium, or the Rule of Conscience (1660) by Jeremy Taylor, I.i.5; commonly rendered into a proverb: "When in Rome, do as the Romans do", or simply "When in Rome..."