He had changed his theme, too, and had chosen one more in consonance with the prevailing vogue. But to the end he had an eye for the charms of the free open face of nature. For the share he took in bringing back into our literature the recognition of these charms, he will ever hold an honourable place in the history of letters. It was from another and somewhat dissimilar part of the Scottish lowlands that a far more powerful impulse than that of Thomson was given by the genius of Burns to the progress of the literary revolution of the eighteenth century. The landscapes of Ayrshire, where Burns was born and spent most of his life, though akin in their main aspects to those of Roxburghshire, present nevertheless certain well-marked differences in topography which were not without their influence on the muse that inspired _Tam o' Shanter_ and _Halloween_. The lowlands familiar to Burns throughout most of his life form a wide and undulating plain, surrounded on three sides by ranges of upland, and on the fourth by the open Firth of Clyde. The heights along the southern side belong to the long and broad chain of uplands which stretches from Portpatrick to Saint Abb's Head. Rising sometimes to more than 2,500 feet above the sea, they stretch as a wide pastoral country, much of which is still covered with 'muirs and mosses many.' These high grounds catch the clouds and mists from the Atlantic, and receive such a copious rainfall as to feed many large streams which cross the lowlands to the sea. The number and size of these streams form a notable feature in the scenery, and the different geological formations through which they flow have contributed to give much variety to their channels. Here they may be seen flowing in a narrow glen, there opening into a wider strath, or creeping sullenly in a narrow chasm between precipitous walls of naked stone, or dashing merrily over rock and boulder beneath overarching trees, or sweeping in wide curves through open meadows or dense woods, and finally carrying their burden of mossy water into the blue firth. These streams, with their endless changes of aspect, their variations from season to season, their play of sunshine and shadow, their wild flowers and their birds, had a strong hold on the affections of Robert Burns. His best inspiration came to him from them. As he tells us himself: 'The Muse, na Poet ever fand her, Till by himsel he learn'd to wander Adown some trottin' burn's meander, An' no think lang; O sweet to stray, an' pensive ponder A heart-felt sang.'[34] In the poem from which these lines are quoted, after alluding to the poetic fame of other streams, while those of his own county remained unsung, the poet declares his resolve to atone for this neglect: