TODAY is the International Day of Families, the tenth anniversary of the campaign by the United Nations to encourage governments, non-governmental organisations and us to put the family at the heart of our concerns.

Like a meteorite entering a gravitational field, the family is disintegrating. In Britain in the past thirty years rates of marriage have halved. Forty per cent of children are born outside marriage. Forty per cent of marriages end in divorce. There are more teenage pregnancies and lone parents than at any time in our history. And it’s all happened for the highest of motives.

I remember the first time I heard the idea of the family being intellectually abused. In 1967, in the course of his Reith Lectures, Sir Edmund Leach said “Far from being the basis of the good society, the family, with its narrow privacy and tawdry secrets, is the source of all discontents.”

What kind of family did he grow up in, I wondered at the time. It didn’t sound like any I knew. I saw honest men and women building a life together, caring for their children and working to give them chances they never had. “Haven in a heartless world” is what Christopher Lasch called his book on the subject, and that sounded closer to what I and my friends had experienced.

But then, I had not yet been exposed to the family’s cultured despisers. I did not know that for Marxists it was the prop of the capitalist economy, or that for some psychoanalysts it was an instrument of emotional repression. I had not yet read Margaret Mead’s study of Samoa, which purported to show that there could be a society based on sexual freedom — a work subsequently shown to be a monumental collection of misinterpretations.

In short, I was just too uneducated to realise that the home I loved and the parents I respected were really “the source of all discontents”.

So, in obedience to noble ideals — freedom, individuality, autonomy — the family was deconstructed. Now, a generation later, we can count the costs: an unprecedented rise in broken relationships, drug and alcohol abuse, depression, eating disorders, stress-related syndromes, physical abuse, teenage pregnancies, child homelessness, psychiatric dysfunctions, suicides and suicide attempts. In the 20 years between 1979 and 1999, while incomes were rising, child poverty in Britain increased by 350 per cent.

Moral judgments are out of place. No one undertook the sexual revolution in order to give children a rough time. But that was the result. Today, in the most important matrix of their lives, too many children face chaos where they need stability. To deprive them of the love and nurture — even just the predictable presence — of those who brought them into being is irresponsible and unfair.

Families are not fairytales whose last line is “and they all lived happily ever after”. They are places of conflict and stress. But they are also places where we learn to resolve them by honest communication, mutual understanding and forgiveness. The family is where we learn the grammar of emotional intelligence by not giving up when the going gets tough. It’s our ongoing seminar on the meaning of loyalty.

Families are where love is written not in poetry but in prose. What is love? Watch a parent caring for a handicapped child. See a spouse coping with a partner suffering from Alzheimer’s disease. Watch a family playing together in a park on a sunny afternoon, or a toddler taking its first steps and falling laughingly into outstretched parental arms. There is a beauty, undemonstrative, unselfconscious, that lives in a thousand small gestures of listening, caring, helping, giving, for no ulterior motive other than the fact that here we are “we” not “I”.

The family is where passion, affection and companionship meet in the most intimate of human bondings. It is where, if we are blessed, we become most like God himself, bringing new life into the world through and for the sake of love. It is our first school, a miniature welfare state, a healthcare centre, a tutorial in responsibility. And yes, there is something spiritual about it. It is solitude redeemed.

The prophet Hosea said it in the name of God. “I will betroth you to me for ever. I will betroth you to me in righteousness and justice, devotion and compassion. I will betroth you in faithfulness.” The family is where selves touch and are transformed: life joined to life in love.

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