IT IS NO SECRET that ideas about what is right and what is wrong vary from time to time and place to place. King Solomon would not be apt to see eye to eye with a Presbyterian missionary on the subject of monogamy. For that reason, a popular argument runs, morality is all relative to the tastes of the time and not to be taken any more seriously by the enlightened than tastes in food, dress, architecture, or anything else. At a certain level, this is indisputably so. But there is another level.
In order to be healthy, there are certain rules you can break only at your peril. Eat sensibly, get enough sleep and exercise, avoid bottles marked poison, don't jump out of boats unless you can swim, and so on.
In order to be happy, there are also certain rules you can break only at your peril. Be at peace with your neighbor, get rid of hatred and envy, tell the truth, avoid temptations to evil you're not strong enough to resist, don't murder, steal, and so on.
Both sets of rules are as valid for a third-century person as for a twentieth-century Norwegian, for a Muslim as for a Methodist bishop, for the emperor Nero as for Marilyn Monroe.
Both sets of rules—the moral as well as the hygienic—describe not the way people feel life ought to be, but the way they have found life is.