On high Ground.-A common observer supposes that water is usually found, and, therefore, most natural, in the lowest ground; but a moment's consideration will evince the error of this supposition. Places abounding in lakes and pools are generally the highest in their respective countries; and without such a provision of nature the world could not be supplied with rivers, which take their source in the highest mountains, and, after innumerable checks to retard and expand their waters, they gradually descend towards the sea. If nature be the model for art in the composition of landscape, we must imitate her process, as well as her effects. Water, by its own power of gravitation, seeks the lowest ground, and runs along the valleys.* If in its course the water meets with any obstruction, it spreads itself into a lake, or meer, proportionate to the magnitude of the obstruction: and thus we often see in the most picturesque countries a series of pools, connected by channels of the rivers which supply them. From certain points of view, these pools, though on different levels, will take the appearance of one continued lake, or river, only broken by islands or promontories, covered with brushwood; and from hence was taken Mr. Brown's frequent attempt of uniting two pools, which could not be brought together in reality, but which become apparently united by an effect of perspective, not always attended to in gardening.
*[Indeed I have sometimes fancied, that, as action and re-action are alike, and as cause and effect often change their situations, so valleys are increased in depth by the course of waters perpetually passing along them: thus, if the water only displaces one inch of soil in each year, it will amount to 500 feet in 6000 years; and this is equal to the deepest valleys in the world. In loose soils, the sides of the hills will gradually wash down, and form open valleys; in hard soils they will become narrow valleys: but ravines I suppose to be the effect of sudden convulsions from fire, or steam, and not made by any gradual abrasion of the surface.]
