BOOKS / Politics? Bah] Humbug]: Christmas Presence: In the last of the series, Sean French reads A Christmas Carol again

There have been so many inferior versions of A Christmas Carol. It has been repeatedly filmed. There is a crude Disney cartoon, a second-rate musical, Michael Caine has played Scrooge in the middle of a cast of Muppets. Lesser works might have been obliterated by such treatment, but Dickens's masterpiece survives untouched, with all its warmth, poignancy and anger.

This novella is probably the work of literature I have read most often - it enthralls me over and over again. Yet I have a problem with it: what is it that the firm of Scrooge and Marley actually does? Dickens shows us the door of their warehouse, with the name of Marley never painted out, but he doesn't trouble to tell us what is kept behind it. The story gives us a child's eye view of business, in which Scrooge's occupation consists of sitting in his counting house, abstractly 'busy', while his clerk, Bob Cratchit, mysteriously sits 'copying letters . . . in the dismal little cell' beyond.

Rudyard Kipling could never have written A Christmas Carol because he loved the rituals, the ethos, the professionalism of work too much to dismiss it as a waste of time and spirit. Dickens makes it easy to denounce Scrooge's arid obsession with business by never specifying what the business is. After all, the poulterers', fruiterers' and grocers' establishments that he describes so lovingly are businesses much like Scrooge's, but Dickens describes them, absurdly, as 'a splendid joke: a glorious pageant, with which it was next to impossible to believe that such dull principles as bargain and sale had anything to do'.

A Christmas Carol masquerades as a work of political protest about the indifference of the prosperous towards the poor. Scrooge tells two gentlemen collecting for charity that if people would, as they have assured him, rather die than go into a workhouse, 'they had better do it, and decrease the surplus population'. The Spirit of Christmas Present predicts the death of Tiny Tim to a dismayed Scrooge in words that could be said with equal effect today, to people who talk, for example, about unemployment as a price well worth paying: 'Man, if man you be in heart, not adamant, forbear that wicked cant until you have discovered What the surplus is, and Where it is. Will you decide what men shall live, what men shall die?'

This is a formidable indictment, but Dickens never - here, or in other works - follows up its implications. A starved, exploited worker such as Bob Cratchit, who sees his children being destroyed in turn by an unjust economic system, must not foment revolution (see Barnaby Rudge, in which the mob is condemned), or even unite with other exploited workers to secure better conditions (see Hard Times, in which the trade union movement is crudely mocked). Instead he must wait for his employer to have a change of heart.

Dickens's failure to write a sensible social democratic pamphlet is not remotely to be regretted. He pretended to write a simplistic fable in order to smuggle in something stranger and more beautiful. He almost gives the game away when he solemnly informs the reader that Scrooge was 'not much in the habit of cracking jokes'. In fact, the wicked Scrooge of the story's first section is distinguished by his constant, savage humour, pouring scorn on every hallowed aspect of the festive season. As he says to his tiresomely cheerful nephew: 'Every idiot who goes about with 'Merry Christmas' on his lips should be boiled with his own pudding, and buried with a stake of holly through his heart.'

Both the comic and the emotional heart of the book lie in the character of Scrooge himself. One of the great subjects of the story is time and loss, our sense of the past with its failures, missed opportunities, roads not taken. Scrooge's first magical journey is back into his own past, where his emotional deprivation is explained by the effects of a family, fallen and humiliated, like Dickens's own.

Some of this story's uncanny power in so short a space can be explained by Dickens's identification with his hero - both men had buried childhood torment in years of unremitting toil. Scrooge doesn't need to be reformed. He only needs to be shown the wrong turnings of his early life to be overwhelmed, much as Dickens was, as the audiences to whom he read these passages were, and, I think, as any modern reader must be.

While pretending to be providing advice on Christmas party games and charity donations, Dickens is exploring our deepest notions about how we, as individuals, can respond to our past and what meaning it can still have for us. Can mistakes be put right? Can we make reparations to our dead? Scrooge cannot change past events or cheat the effects of time. He cannot apologise to his dead sister, or marry his estranged fiancee - now married and with children. But he can at least be better friends with his sister's son. And the relatively malleable future can be dealt with before it becomes the irredeemable past.

Dickens writes vividly about the Christmas feasts and dances, but the more haunting moments are private, portrayed in glimpses, such as Scrooge's visit to the ship's officers, far out at sea, 'ghostly figures in their several stations; but every man among them hummed a Christmas tune, or had a Christmas thought, or spoke below his breath to his companion of some bygone Christmas Day, with homeward hopes belonging to it'. His Christmas is a collection of moments, delicate, brief, agonisingly precious.