Even at the present time nocturnal illusion still recalls these images of the past. When the rapidly rising and descending constellations illumine the margin of the plain, or when their trembling image is repeated in the lower stratum of undulating vapour, we seem to see before us a shoreless ocean.[3] Like the ocean, the Steppe fills the mind with the feeling of infinity; and thought, escaping from the visible impressions of space, rises to contemplations of a higher order. Yet the aspect of the clear transparent mirror of the ocean, with its light, curling, gently foaming, sportive waves, cheers the heart like that of a friend; but the Steppe lies stretched before us dead and rigid, like the stony crust[4] of a desolated planet. In every zone nature presents the phenomena of these great plains: in each they have a peculiar physiognomy, determined by diversity of soil, by climate, and by elevation above the level of the sea. In northern Europe, the Heaths, which, covered with a single race of plants repelling all others, extend from the point of Jutland to the mouth of the Scheldt, may be regarded as true Steppes,--but Steppes of small extent and hilly surface, if compared with the Llanos and Pampas of South America, or even with the Prairies of the Missouri[5] and the Barrens of the Coppermine river, where range countless herds of the shaggy buffalo and musk ox. A grander and severer aspect characterises the plains of the interior of Africa. Like the wide expanse of the Pacific Ocean, it is only in recent times that attempts have been made to explore them thoroughly. They are parts of a sea of sand, which, stretching eastward, separates fruitful regions from each other, or encloses them like islands; as where the Desert, near the basaltic mountains of Harudsh,[6] surrounds the Oasis of Siwah rich in date trees, and in which the ruins of the temple of Ammon mark the venerable site of an ancient civilisation. Neither dew nor rain bathe these desolate plains, or develope on their glowing surface the germs of vegetable life; for heated columns of air, every where ascending, dissolve the vapours, and disperse each swiftly vanishing cloud.