There are some Scottish authors and their works we expect to find in every bookshop. There would be the collected works of Robert Burns, the novels of Sir Walter Scott, Robert Louis Stevenson's Kidnapped, Lewis Grassic Gibbons's Sunset Song, perhaps Blind Harry's poem The Wallace, if Braveheart has been on TV again. On the other hand, we expect to have to put in more work to track down the poems of Robert Fergusson, David Lindsay's A Voyage to Arcturus (from 1920, the first Scottish science-fiction work) or the other novels of Dame Muriel "Jean Brodie" Spark, such is the low current awareness and demand.

Of more recent writers, Alasdair Gray, A L Kennedy and James Kelman will be prominent on the shelves, but James Kennaway, Alexander Trocchi and Gordon Williams might involve a trip to a second-hand bookshop.

The simple fact is that books, in common with such fashion statements as spats, corduroy dungarees or Chinese slippers, have their times and their hours. While Burns, Scott and Stevenson seem to have secured a permanent place in the popular national canon, their contemporaries, such as James Hogg, John Galt and Susan Ferrier, have not been swept along on quite the same tide of lasting popularity.

So what determines the longevity, or the periodic revival, of a given book or author?

Some are kept afloat by societies of admirers (such as the Robert Burns World Federation, the James Hogg Society or the Robert Fergusson Society), some by the publishing subsidies of the Scottish Arts Council, and others by being continually placed on school and university reading lists.

Marshall Walker, the Glasgow-born and educated professor of English at the University of Waikato in New Zealand from 1981 to 2006, had enough distance from his native country and its literature to write the authoritative Scottish Literature Since 1707. In it, he wrote that "the canon has lost its normative status, its imperious proscriptive force and its exclusivity".

In poetry, for example, the work of Tom Leonard, Robert Crawford and Edwin Morgan, both as poets and as critics, has ensured that James Thomson's masterpiece, The City of Dreadful Night (1880), must now be included in the British canon. The growth of feminism, Walker adds, has brought renewed interest in Jean Elliot (The Flowers of the Forest, 1776), Anne Barnard (Auld Robin Gray, 1771), Margaret Oliphant (The Marriage of Elinor, 1892) and Catherine Carswell (Open the Door!, 1920).

The fall of the British Empire and the concomitant rise in regional cultures has ensured that voices and views from around Scotland, and in particular the Gaeltacht, have been brought into the inclusive spotlight of a more inclusive and more confident Scottish culture.

But what of the classic trio, Burns, Scott and Stevenson? Burns has a high literary profile in part because of his visibility around the country. There are annual ritualistic meals in his honour, he has been practically made a saint by Freemasons, and he cleverly - for a lowlander - declared "My heart's in the Highlands". He also moved around enough in life to be honoured with statues from Aberdeen to Dumfries (not to mention Canada, the US and Australia), and to have both his place of birth and burial made into shrines. At Alloway, where his childhood home is now a museum, the Burns National Heritage Park celebrates his life and work. "Nowhere captures his legacy both more effectively and authentically," claims the park's publicity material. His mausoleum, in St Michael's Churchyard, Dumfries, attracts pilgrims from around the world. That said, most of the devotees of the Burns cult could do little more than reel off a few of his lighter verses, or name a handful of his more serious works.

Burns is a bard for all seasons. As the heritage park publicity notes, he can be held up as a "humanitarian, national hero, poet and musician, lover and international icon". Most people can find something to amuse themselves in one or more of these descriptions, which makes Burns as a brand appealing to people across a wide spectrum.

Scott, on the other hand, is remembered for a shelf-ful of unread and, today, possibly unreadable novels (as someone said, if you see the word tree, skip two pages), and for killing himself with overwork to pay back the creditors of his collapsed printing company.

Stevenson, too, has a one-dimensional life as the Edinburgh littérateur who headed further and further west in search of better weather for his health. In the popular imagination, Burns is a one-man soap, while Scott and Stevenson are BBC4 documentaries.

In the twentieth century, Hugh MacDiarmid, too, was a multi-dimensional master of splutter and spin, sometimes a bit too keen to believe his own PR, and sometimes a bit too keen to zig when others were zagging, just for the (deadly serious) fun of it. As the inflater-in-chief of the bouncy castle that was the Scottish Renaissance of the 1920s, he believed he had the power to make or break reputations. Others believed this, too, unfortunately, and the works of William Souter and, to some extent, Edwin Muir have suffered for it since.

The reputation of Lewis Grassic Gibbon has fallen, occasionally buoyed up by the repeat of the BBC Scotland dramatisation of Sunset Song, and John Buchan's book sales have gone the way of his outdated imperialism, except perhaps for the three film versions of The Thirty-Nine Steps.

It would seem that the way to stay in the book-buying public's mind is to have a brand, as the marketers have it, that has a good story to tell, and to have as many styles and periods of writing as possible, so that people of all types can claim you as their own. Just as Thin Elvis (the country boy who brought black rhythm into white pop music) and Fat Elvis (all rhinestones and patriotism) have their admirers, those Scottish writers who can be versatile will always find a home on the best-read, if not the best-selling, lists.