When the heats of summer have dried up the streams, and cataracts only trickle and drip, and the dams of brooks and rivers cease to pour the arching crystal from their lips, I have always loved to explore the forsaken water-courses. An imprisoned fish, a shell with rainbow lining, a curiously-worn rock, a strangely-tinted and grotesquely-fashioned stone--these are always objects of interest. Then to sit down upon a ledge that has been planed off by ice, and smoothed by the tenuous passage of an ocean's palpitating volume, and watch the shrunken stream slipping around its feet, and hear the gurgle of the faintly-going water, and growl so drowsy with the song that it breaks at last into surprising articulations, and talks and laughs, and shouts and sings--ah! this, indeed, is enchantment! There are few men, I suppose, so fortunate as to have enjoyed a country breeding, who do not recall scenes like this,--who do not remember a half-holiday, at least, spent in the bed of a summer stream, and at the feet of scanty cataracts, making fierce attacks on water snakes, watching lizards lying among the stones of an old raceway, creeping up, hat in hand, to a gauze-winged devil's needle that shivered on a sunny point of rock, and looked as if it might be the ghost of a humming-bird, starting to mark the sudden flight and hear the chattering cry of the king-fisher as he darted through the shadows and disappeared, and noting the slim-legged wagtail, racing backward and forward upon the border of the stream. Among the objects of interest very often, if not always, to be found at the feet of dams and cataracts, are what people call "pot-holes." They are round holes worn in the solid rock by a single stone, kept in motion by the water. Some of them are very large and others are small. When the stream becomes dry, there they are, smooth as if turned out by machinery, and the hard, round pebbles at the bottom by which the curious work was done. Every year, as the dry season comes along, we find that the holes have grown larger and the pebbles smaller, and that no freshet has been found powerful enough to dislodge the pebbles and release the rock from their attrition. Now if a man will turn from the contemplation of one of these pot-holes, and the means by which it is made, and seek for that result and that process in the world of mind which most resemble them, I am sure that he will find them in a man of one idea. In truth, these scenes that I have been painting were all recalled to me by looking upon one of these men, studying his character, and watching the effect of the single idea by which he was actuated. "There," said I, involuntarily, "is a moral pot-hole with a pebble in it; and the hole grows larger and the pebble smaller every year."