News that Alasdair Gray is making a promising recovery from serious illness is more than cheering. After a fall last June, in which he broke his back, the novelist, painter and polemicist has been in hospital. He told the Herald last week that he has had a tracheostomy, and although he still cannot walk, is starting to regain his strength. “I’m not too bad,” was his typically upbeat and unself-pitying assessment of his medical condition. Although it is likely that his recuperation will be lengthy, it was the first positive news we’d heard of him in a long time, and a flood of good wishes will doubtless have been sent his way through the ether, and more than a few glasses raised to him too.

It’s hard to think of many artists and writers who are as admired or liked as Gray. While talent partly explains his popularity, so does his sense of humour. In the first edition of his extraordinary novel, Lanark, he inserted a bookmark in which a doctor of literature answers questions from the worried public: “I think I have caught Lanark,” writes one. “What can I do about it?”.The reply is comforting: “There is nothing to be ashamed of in having Lanark. Although it is what we doctors call ‘incurable’, many sufferers – acrobats, philosophers and popes – manage to lead a normal, healthy life.”

This was true – up to a point. The day in February 1981 when Canongate sent this piece of imaginative genius out into the world was a turning point for modern Scottish fiction, but also for the country itself. It was as if one of the Stevenson lighthouses had been lit up so brightly that everyone, from Wick to Wigtown, could see more clearly who they were and what they wanted to do. Nor was reading Lanark an entirely curable condition, despite what the doctor said.

This mercurial novel got into the nation’s bloodstream, where it fizzed and bubbled and produced such an imaginative ferment you’d have thought we had been nibbling on yeast. Immediately recognised as brilliant – Anthony Burgess considered it the finest Scottish novel since Walter Scott – it has been cited as an influence on writers as diverse as Janice Galloway, Irvine Welsh, Iain Banks and Ali Smith.

With Lanark, Gray put Scotland onto the cultural map in a way that revealed how, in certain ill-educated or prejudiced quarters, we had for almost a century been considered the barren, ignorant north. Though other novelists before him had used Glasgow as their setting, none had depicted it with such artistic vigour or style. Far from flattering – though Edinburgh comes off badly too – it was palpably a love letter to the city that has been Gray’s home and inspiration for 80 years.

His significance, of course, stretches much further than Lanark. As an artist and writer his personality and perspective are stamped all over Glasgow: in his murals at Hillhead tube station, Oran Mor theatre, and the Ubiquitous Chip; on the shelves of bookshops, where his novels and short stories leap out, thanks to his distinctive jacket illustrations; at the Kelvingrove Gallery and Museum, which housed a retrospective of his work; at the Edinburgh International Festival, where David Greig’s adaptation of Lanark for the Citizens’ Theatre was staged this summer; and in the Hidden Lane Gallery, where an exhibition celebrated his long career in printmaking.

Despite such acclaim, he is a living repudiation of the fashion for aggrandizing self-promotion. Short and bespectacled, Gray has described himself as having “the lean, muscular legs and small bum of the brisk pedestrian but the bulging paunch of the heavy drinker, the fleshy shoulders hunched too near the ears of the asthmatic with bronchial tendencies”. As distinctive a figure as Billy Connolly or John Byrne, he is the embodiment of the quicksilver but diffident artist: brought up in an ordinary family (though it was anything but), a pricker of pomposity in others but even more so in himself; uninhibited in discussing and writing about sex, and outspoken on sensitive subjects such as the distinction between ‘settlers’ and ‘colonists’ in the arts community. His range of artistic expression, generosity towards other writers and painters, and engagement with political issues and ideas of nationhood and independence have been of incalculable benefit to the arts and public discourse. In all of this he represents and enriches the entire country, not just his postcode – and far beyond our borders too.

These months of his illness have been oddly troubling. For 60 years and more, Gray has been so hard at work he hums like a beehive. While he has been in hospital, it has felt as if the wheels of a great engine have stopped turning. Rumours suggest, however, that he might still be writing. Get well soon, sir. Glasgow and Scotland need you.