Those who have already digested the programme for this year's Aye Write!

book festival in Glasgow next month may have noticed an event called Scotland's Bookshelf, as well as several spin-off sessions linked to that title. Scotland's Bookshelf is the name of an imaginative and one might say daring, even reckless, notion to select 20 of the best books by Scottish writers of the past century and run extracts in a free booklet, as part of Glasgow's annual City Read. It was conceived to mark the Mitchell Library's centenary at Charing Cross, and as one of the judges I found the exercise not just difficult, but excruciating. It was, however, most illuminating.

I won't list the books we chose – you can find them on the Aye Write! website, in the printed programme or, as of March 10, as a free book in Glasgow public libraries. But I must say that while the rest of Europe has been lying awake fretting over triple-A ratings, I've been more concerned about the fact our list of 20, excellent though the individual titles are, is a very partial snapshot of the century's great books. To be honest, a doily might be a better image, given the number of holes it inevitably contains. For every book we chose, there were several others clamouring to get in, pressing their noses against the window, as it were, and begging to get close to the fireside. The guilt induced by leaving them shivering on the doorstep is a recipe for insomnia, I can tell you.

On the bright side, there could have been no better exercise for reminding me what an astonishing heritage of fine books Scotland produced in the 20th and early 21st centuries. I don't want to beat a Little Scotlander drum, but whatever classics other nations have produced in the same period, Scotland can hold its head up as an equal.

However, what is even more interesting, as one scrolls through the decades, is to observe recurring themes. At first it's hard to see what connects a novelist and poet such as Violet Jacob (who published her most famous work, Flemington, in 1911) or George Blake's novel The Shipbuilders (1935) with the likes of Irvine Welsh or AL Kennedy. Yet what slowly becomes obvious is that with a handful of notable exceptions, Scottish writers often work on part of the same canvas and use a similar palette.

The social and economic conditions of ordinary people, the plight of outsiders, the flashpoints in Scotland's political history, and the profound and often malign influence of place upon character and fate are common sources of inspiration, whether in Neil Munro's The New Road, about the hated General Wade's feat of road building, or AL Kennedy's war novel, Day; Jessie Kesson's The White Bird Passes, or James Kelman's Greyhound For Breakfast; Nancy Brysson Morrison's The Gowk Storm, or Robin Jenkins's The Cone Gatherers.

Not surprisingly, the majority of Scotland's writers come from a left-of-centre and anti-authoritarian position, though there are noble exceptions. I suspect that's why fiction set in the past is so popular a form of storytelling, writers finding in the great sob stories and triumphs of Scotland's dark history a colourful emotional and political stage on which to explore the nation's psyche and its fortunes. Even science fiction echoes this ultra-democratic cast of mind, as does much non-fiction, from histories and biographies, to political and cultural analyses.

One final thought: why have so few authors beyond, say, Lewis Grassic Gibbon, Hugh MacDiarmid and, most recently, James Robertson, dealt with an epic span? Is the tightness of focus seen in our literature a reflection of the country's size, or is it the expression simply of an instinctual talent for economy and directness? I'm afraid I have no answer to that, which probably means more sleepless nights ahead.

Scotland's Bookshelf is on March 10 at 8pm. For tickets call 0141 353 8000, or visit