LISE is a strange, single woman in her thirties.

She works for an accountancy firm, perhaps in Denmark. Her behaviour is erratic and she is often contrary. Told by an assistant in a clothes shop that the items she has chosen might not go together, she says, "People here in the north know nothing about colour."

Lise, it seems, knows what she wants and how to get it, which is someone to kill her. Soon, we learn, she will be found "dead from multiple stab wounds, her wrists bound with a silk scarf and her ankles bound with a man's necktie".

This, then, is the premise of Muriel Spark's macabre novella, The Driver's Seat. First published in 1970, it was shortlisted for the Booker Prize. But while she thought it the best of her books, which of course include The Prime of Miss Jean Brodie, the wider reading public proved largely impervious to its charm. A movie of the same name did not help to increase its popularity. It starred Elizabeth Taylor as the enigmatic Lise who, remarked Spark, acted as if she'd rather have a martini than be murdered.

Had she so wished, Lise could have killed herself, but that would have been suicide which, probably for religious reasons, she cannot contemplate. Her solution, therefore, is to find someone who will do what she cannot. Technically it is murder but it could be argued that it falls into the category of assisted suicide.

It is doubtful whether members of the Health and Sport Committee, which met at Holyrood yesterday to grill expert witnesses on the Assisted Suicide Bill, have read Spark's book. But as the creme de la creme of Scottish letters was well aware, this is an area that is fraught with controversy and moral and legal dilemmas. There is a need, therefore, to tread warily and sensitively. Meanwhile, an Assisted Dying Bill is about to come before the House of Lords, which may yet prove its undoing; this despite the fact that opinion polls consistently show there is considerable support for legislation which allows people to decide when they might like to end their lives.

It is a subject that one would rather not have to confront. When I was younger I thought suicide an abomination and a form of cowardice. Indeed, even now when I read about someone taking their own life while, simultaneously, asking for the forgiveness of their family, a shiver of revulsion goes through me. I have had several friends who killed themselves, one when we were both in our late teens. To this day I have no idea why he did it. He wasn't ill or, as far as I could tell, unhappy or unbalanced. But one night he took an overdose and lapsed into a comma from which he never emerged. Some said that was not what he had intended, others that it was a cry for help. Whatever it was, the result was the same.

The assisted suicide bill, however, is not concerned with angst-ridden, emotionally fragile youth but with those who, through illness and infirmity, have come to the conclusion that living has become intolerable. Its original sponsor was Margo McDonald, who suffered from Parkinson's disease and who died a year ago. She always insisted that when the time came she would rather die than survive as a burden to her family and a shadow of her ebullient, glittering self. Hers was a rational, well-considered argument which, in the end, she did not have to test in practice. Others, however, are condemned to live on when they would rather not. But often by that point they are incapable of acting on their own behalf and require the help of others to transport them from this world to whatever lies beyond.

That there is need for clarity on this most difficult of issues is obvious. My own feeling is that assisted suicide should only be permissible when we can be sure that the person who wants to die is sound of mind if not of body. Thereafter how this is to be achieved must be expedited in a dignified manner and with no threat of prosecution hanging over those involved. Doctors and nurses, moreover, who do not want any part of it should be allowed to opt out. Life-saving, not life-ending, must be their job description.