It is safe to assume that, as you read this, there is a distressed child in a residential care centre or a special school somewhere in Ireland who desperately needs comforting, and that there is a care worker there who is afraid to put an arm around him or her.

Because other people in authority over children have betrayed their trust, this child cannot be comforted, and a childcare worker cannot show the affection that he or she would, perhaps, like to show.

These others, these child-abusers, have damaged this child whom they have never seen and they have obliged childcare workers to act as though they could come under suspicion at any time.

A few months after the closure of Madonna House one of their former staff rang this newspaper to say how difficult her erstwhile colleagues were finding it to get jobs in childcare.

The vast majority might have been innocent of any wrongdoing and unable to do anything about what had gone on there, she said, but saying they had worked in Madonna House put them at a huge disadvantage. So stigmatised did they feel that they would not meet our reporter, even in a group, and indeed they have been quite invisible in the sporadic debate about Madonna House.

The abusers have poisoned the well for all of us. Actions which in the past had a ring of virtue now have a taint of suspicion.

One evening last weekend when I was walking along the Grand Canal near Rialto in Dublin, a young girl of nine or 10 called to me.

"We need help," she said. She and her young brother were trying to untangle the hook of their fishing line from weeds in which it was caught.

I retrieved the hook for them, to their great relief, and went off feeling virtuous. And then I began to wonder just what anybody who knew them and who happened to be looking out their window would make of this white-haired stranger in a raincoat approaching two small children on a canal bank.

The nervousness is everywhere. Guidelines issued for volunteers in sporting organisations for young children a few years ago advised them against being alone with a child in their car. A kindness such as giving a child a lift is suddenly an occasion of suspicion.

Reputations suffer en masse thanks to the minority of abusers. In the 1960s, when too many families lived in a degree of poverty that would defy belief now, and when care for deprived or handicapped children was provided in institutions, a movement began to change all this and to create the system of community services we take for granted today.

It was initiated by Mary Campion, a member of the Sisters of Charity in Kilkenny. Bishop Peter Birch put the power of the diocese behind the establishment of what became Kilkenny Social Services.

The Sisters of Charity seconded nuns to the new service at no cost. One of them was Sister Stanislaus Kennedy.

They started a revolution in social services, yet it is Sister Stanislaus who had to defend herself this week, and not the people who beat and abused children in institutions. Everybody is tarred by the few.

And it can touch anybody. For example, do any readers know of a nursing home in their area which they would advise people to avoid at all costs? Perhaps you have heard gossip about what goes on, perhaps you are a doctor who has occasion to visit nursing homes, or perhaps you have worked in the home.

What are you going to say in 20 years' time if somebody sticks a microphone in front of you and asks what you did about it? Maybe you will say: there was nothing I could do, or everybody knew about it, or I trusted the health board to pick up on it when it inspected the place.

But, your interrogator asks, you knew, didn't you, that something was wrong? And you did nothing, did you? You stood by and you let it happen, didn't you?

Are you really any better than the person who starved or assaulted or humiliated the residents, are you?

This would all be grossly unfair to you, but it shows how abusers damage not only their unfortunate victims but other people, too; in this case the reputations of people who actually did nothing wrong themselves. (It also shows how easy it is to blame other people for not having done what we probably wouldn't have done either if we had been in their shoes).

The abusers have poisoned and distorted society. The poison goes from generation to generation. Some people abused in institutions talk of wrecked marriages, alcoholism and crime stemming from the harm done to them by their abusers. The spouses and children of these marriages, the victims of crime, alcoholism and drug addiction are victims of the abusers, too.

When the Commission on Child Abuse begins its hearings we need to understand that this is not only about "them", the ones who were abused, but it is also about us, whose institutions and customs have been warped by abuse and who have to find a way to make it safe again for a decent, concerned adult to hug a crying child.