This is what the psychiatrists mark consulted told him. They didn't tell him that depression being caused by a chemical imbalance in the brain is not a fact but a hypothesis for which no scientific evidence has ever been found. David Healy, Professor of psychiatry at Cardiff University and world renowned for his research into SSRI drugs and depression, calls it a myth. (See his book Let Them Eat Prozac).

Mark consulted Graham Thornicroft at the Institute of Psychiatrists (sic - probably the Institute of Psychiatry in London) who told him about the prevalence of mental illness in the UK, and Tim Cantopher, psychiatrist and author of Depressive Illness: Curse of the Strong. Cantopher said, 'If you try to do the undoable, you're going to get this. Stress doesn't make you ill. You do - by trying to do the undoable.'

Mark wrote, 'If I'm honest, I have been trying to do the undoable for years. . On paper [my life] looked marvellous. In reality it made for long years of chaotic breakfasts, a messy school run, some exercise, a dash to London, 10 hours on a pinball newsdesk, back to release my wife for a school governors' meeting or a conference call or to move the house slightly to the left. Late for everything.'

Many of the emailed comments about Mark's article commended him for describing just what the experience of depression felt like. However, on the following Saturday August 7 there was a group of letters in the Guardian that took him to task for calling depression an illness.

Paul Reading, lecturer in mental health as the Open University, called Mark's article 'moving' but went on to say that it had only one flaw. 'He refers to succumbing to an "illness". This reliance on the medicalisation of mental distress is a continuing dilemma for both survivors of such experiences and those employed to help them.' Andrew Cooper, Professor of social work, Tavistock and Portman NHS Foundation and Felicitas Rost, project Co-ordinator, Tavistock Adults Depression Study wrote, 'There is increasing evidence that mental health problems are developmental in nature, and up to three quarters of adult difficulties start in childhood. Psychotherapy frequently reveals present and past losses, in keeping with known risk factors. Drugs and brief cognitive therapies can help greatly, but they do not engage our complex histories, the rejections, separations and bereavements revived by current adversities. Sometimes it is the loss of our cherished idea of ourselves that precipitates "breakdown". If we have not mourned these experiences fully they persist, corroding our self-esteem.' Jeremy Goring of St Leonards-on-Sea pointed out that what Mark had experienced was an acute feeling of 'dis-ease'. He was pleased that Mark had 'discovered the truth of the saying that there is always learning in the depression.'

Mark lived a life of extreme busy-ness. If he had asked himself, 'Why is it important to me to do all these things?' and answered it honestly he would have discovered something that he had known all along, that he was a good person and, like all good people, he believed that, no matter how hard he worked and how much he tried to please everyone and not let anyone down, he was never good enough, and that, if he let someone down, that person would reject and abandon him forever.

No one is born believing that, 'As I am I am not good enough. I have to work hard to be good.' However, we are born needing to make a bond with a mothering person. When such a person appears we soon learn that, in order to keep this person's benign attention, we need to be good in the way this person defines 'good'. Some mother might define their baby's 'good' as not making a mess, not making a fuss and quickly learning to be toileted trained, while other mothers might define 'good' as being very loving to mummy and looking after her, and so on. For some small children the fear of not living up to their mother's expectations and being rejected and abandoned by her is so intense that earning their parents' love becomes central to their sense of who they are as a person. When in adult life they become depressed and cast around for an explanation why, they cannot see what is right in front of them, their need to be good and their fear of being annihilated as a person - what Mark called disintegrating.

Mark did spend some time with a therapist, for how long he did not say. He wrote, 'Therapy taught me that I am not who I thought I am, that some of my reflexes and instincts are unhealthy.'

In contrast, in his wise and wonderful book Family Romance, John Lanchester described his periods of long and intense panic after his father died. Lanchester, an extravert like Mark, makes very clear his fear of rejection and being abandoned, all by himself in the world. Finally, he entered into a long period of therapy. He wrote, 'I would say that the things that psychotherapy has helped me with have to do with feeling my feelings as and when I'm supposed to feel them, rather than mediated into mysterious mood swings or (worse) emerging as a form of panic. It helped me face painful feelings related to loss and abandonment; it helped me make sense of myself; it helped me deal with the illness and death of people I loved; and it helped me to write. It did that by helping me spend more time in my head without panicking. It helped me sit still, which is something you have to learn to do if you're going to write books.'

Mark did learn 'how to let time pass without trying to fill it'. But he did not learn everything that depression could teach him.

The best book about the experience of depression that I have ever read is Gwyneth Lewis's Sunbathing in the Rain: A Cheerful Book about Depression. In this she wrote, '[Depression's] purpose is to teach you how to avoid becoming depressed again. In that sense, depression is a very kind disorder, and will return only if you refuse to learn the lessons it has to teach you.'

Mark described how he gradually became alive to the world again. However, six weeks after going back to work he relapsed 'and need another month to build up from the bottom again. Even now, a year on I still feel the sharp edge of something, But, happily, it does little more than prod me, remind me that I need to tread carefully.'

Mark has not learned how to avoid becoming depressed again. Life is never without adversities. The chances are that he will become depressed again until, as Gwyneth said, he learns the lesson that his depression can teach him.