Cultural Omnibus. If you think of kiltclad highlanders when you hear the word `Scots,' think again. This year's Edinburgh Festival will show you a Scotland you won't recognize.

IT seems only right: The glories of Edinburgh, capital of Scotland, ought for once to be more in the foreground of its namesake festival. This year's Edinburgh International Festival of the Arts -- which claims with some justice to be the world's largest -- takes as one of its main themes that 18th-century phenomenon ``The Enlightenment'' -- ``The Scottish Enlightenment,'' to be precise. Among other things, this provides an opportunity to celebrate the ancient Scottish city itself as something more than a glorious, taken-for-granted backdrop to the three-week cluster of cultural events that takes over the city each year (the occupation will begin on Aug. 10 this year).

The latter half of the 18th century was Edinburgh's Golden Age: The consummate classical architecture of the New Town and Edinburgh University remains as magnificent witness to this remarkable period of ``improvement.''

But the Scottish Enlightenment was something more than fine architecture alone. David Daiches, a well-known British scholar, describes it as an ``extraordinary outburst of intellectual activity.'' The claim is that between about 1730 and 1790 Scotland became briefly ``the cultural leader of Europe.''

Exhibitions, plays, concerts, and an opera appear as ``Enlightenment events'' in this festival.

But the the festival boasts one major exhibition that concentrates entirely on the subject. It's called ``A Hotbed of Genius: The Scottish Enlightenment 1730-90'' and can be found at the Royal Museum of Scotland, Queen Street (to Sept. 2).

The exhibition -- which was put together by Edinburgh University's Institute for Advanced Studies in the Humanities -- has two parts. The first is designed for the uninitiated; it's ``a walk through the 18th-century Edinburgh with words and music.'' With your own private earphones picking up a sound track, you can glean a general (if rather confusing) notion of the Enlightenment's main concerns as you wander through simulations of dark back streets, a tavern, and then a room of enlarged engravings lit by ultraviolet light. All of this is as entertaining as it is informative.

Not so upstairs. Here we find the main burden of the exhibition, which is described by Peter Jones of Edinburgh University as ``unashamedly instructive.'' It's a fair description, but shouldn't deter anyone really interested. This is not an exhibition to skip round. It asks to be studied, slowly.

It might easily have qualified as an art exhibition, too. This is the time when Scottish portraiture produced some of its finest works. There are a few such portraits on view -- such as Sir Henry Raeburn's fresh, slightly tense oil of Hugh Blair, Presbyterian minister and man of letters, or Allan Ramsay's of David Hume, philosopher and historian (an image of intellectual certainty). Also shown is Ramsay's portrait of Jean-Jacques Rousseau, done at Hume's request. Rousseau wears Armenian costume, and his face wears a look of placid wariness.

But many of the works of art used to illustrate various points are photographic reproductions -- not originals. This seems a pity. Couldn't the organizers have borrowed from the British Museum, for example, James Gillray's splendidly funny caricature print of ``Sir William Hamilton as one of his own vases,'' in the section about the Grand Tour? The reproduction of it is adequate, but it underlines the sense that this exhibition of pictures and books, manuscripts, and memorabilia has not quite escaped the dust of academic library shelves.

This aside, it is a thoroughgoing array of intriguing historical facts and thought-provoking quotations. It certainly rouses interest in the giant figures of the Scottish Enlightenment and stimulates ``further reading'' (conveniently provided in the form of an excellent new book also called ``A Hotbed of Genius,'' which was recently published by Edinburgh University Press, available at the exhibition). Here we find out about such men as David Hume, thought by some to be the greatest philosopher ever to have written in English. Then there's Adam Smith, pioneer economist and author of ``An Inquiry into the nature and causes of the Wealth of Nations.'' Smith would have been remembered as a social philosopher even if he had never written a word of that book; his economic writings were only part of his overarching work on political and social evolution. One of his ideas was that man's conscience is like an ``impartial spectator'' that observes our acts and judges them. Like many of the other ``men of genius'' in Edinburgh of that era, Smith emphasized the basic benevolence of man. ``Howsoever selfish mankind may be supposed,'' he wrote, ``there is evidently some principle in his nature, which interests him in the fortune of others. By imagination we place ourselves in his situation.''

A nice touch in this part of the exhibition is a card of steel pins: Smith used the production of steel pins to illustrate his thesis of the virtues of division of labor.

We also see Smith's inkstand and snuffbox and learn (according to Alexander Carlyle) that ``he was the most absent man in company ... moving his lips and talking to himself.... If you awakened him from his reverie he immediately began a harangue.''

There are also looks at James Hutton and his impact on geology, Joseph Black, chemist and physician who discovered carbon dioxide, William Robertson, historiographer, Robert and James Adam, the famous architect brothers, and many, many more.