Law is twofold -- natural and written. The natural law is in the heart, the written law on tables. All men are under the natural law.

When in Rome, live as the Romans do: when elsewhere, live as they live elsewhere.

A duty is to be chosen from what is virtuous, and from what is useful, and also from the comparison of the two, one with the other; but nothing is recognized by Christians as virtuous or useful which is not helpful to the future life.

When in Rome, live as the Romans do; when elsewhere, live as they live elsewhere.

When I go to Rome, I fast on Saturday, but in Milan I do not. Do you also follow the custom of whatever church you attend, if you do not want to give or receive scandal.

It is ingrained in all living creatures, first of all, to preserve their own safety, to guard against what is harmful, to strive for what is advantageous.