What's the origin of the phrase 'When in Rome, do as the Romans do'?
Why should an English proverb single out Rome and Roman values as especially to be emulated? Couldn't we have had a 'when in Ipswich, do as the Ipswichians do' for example? As it turns out, it's all to do with the travel arrangements of a couple of early Christian saints.
St Augustine: Letters Volume I was translated from the Latin by Sister W. Parsons and published in 1951. Letter 54 to Januarius contains this original text, which dates from circa 390AD: