When did we lose the culture of civility? When did anger become a political weapon? When did the era of gentleness die, to be replaced with our current age of rage? One thing is certain: this is a dangerous development, and we must pull back from the brink.

Often the origin of words tells a story. “Civility” comes from the same root as civilian and civilisation. “Polite” has the same origin as politics and polity. “Urbane” derives from the same root as urban. All three come from Classical words meaning a city and its governance. Why so?

In antiquity, cities, especially those on the Mediterranean, were where people of different faiths and cultures came together to trade. They had to learn to trust one another. They had to develop an ethic that worked with strangers as well as friends. That is where civility was born.

Trade has usually had a bad press. The truth is, however, that business is the most powerful alternative to war. The great trading centres — 16th-century Venice, the Netherlands in the 17th, London in the 18th — tended to be at the cutting edge of tolerance. Often the choice has been, and will continue to be, between the market and the battlefield.

Religion’s greatest strength and greatest weakness is that it creates communities of the like-minded. Members of a faith feel a kinship. They come to each other’s aid. They live the We as much as the I. Often they see themselves as an extended family. That is the good news.

The bad news is that communities distinguish sharply between insiders and outsiders, Us and Them, the saved and the damned, the children of light and the children of darkness. This is not a problem if you live among those who believe as you do, which is what tended to happen in rural communities. But cities were arenas of diversity. That is why they gave rise to an etiquette of civility.

Civility’s virtues — courtesy, restraint, respect for others, understatement — are not universal. They emerge at specific places and times. One of the first modern works on the subject, Adam Ferguson’s The History of Civil Society (1767), was set against a background of urbanisation, the division of labour and the growth of the market economy. It came from the same world as his fellow Scotsman Adam Smith’s The Wealth of Nations.

Civility is an ethic across boundaries. It means respecting strangers. It is a way of saying that though we come from diverse backgrounds, we share a moral universe. Though we are different, we belong to something — the common good — that embraces us both. Without civility there is no society, merely the clamour of individuals and the clash of conflicting ghettos.

We are losing civility. You hear this in the angry exchanges in radio or television interviews. You see it in the vicious slogans on posters at demonstrations. You feel it in the way once-neutral institutions — universities, professional bodies, even charities — have become politicised, engaging in boycotts and tendentious simplifications of complex issues.

Time and again we are invited to take sides on matters where once we felt it important to make space for all sides. When everything becomes politicised there is no place left for personal friendship across dividing lines: what used to be called “dining with the opposition”. It is the beginning of the end of the gracious society.

Why has it happened? Because we have lost a shared moral code. Because we no longer respect authority. Because national identities have eroded. Because we have sacrificed shared responsibilities in favour of individual or group rights. Because the media loves conflict. Because anger gets attention, and rage gets respect. Because the loudest voice wins.

“A soft answer turns away wrath,” says the Book of Proverbs, “but a harsh word stirs up anger.” “Reckless words pierce like a sword, but the tongue of the wise brings healing.” Verbal violence, the Bible suggests, is a prelude to physical violence. Those who cannot sustain a civil conversation will eventually find it impossible to sustain a civilisation. The sooner we recover civility, the better.

Rabbi Sir Jonathan Sacks is the Chief Rabbi of the United Hebrew Congregations of the Commonwealth