As soon as nature gradually vanishes from human life—that is, in proportion as it ceases to be _experienced_ as a _subject_ (active and passive)—we see it dawn and increase in the poetical world in the guise of an _idea_ and as an _object_. The people who have carried farthest the want of nature, and at the same time the reflections on that matter, must needs have been the people who at the same time were most struck with this phenomenon of the _simple_, and gave it a name. If I am not mistaken, this people was the French. But the feeling of the simple, and the interest we take in it, must naturally go much farther back, and it dates from the time when the moral sense and the æsthetical sense began to be corrupt. This modification in the manner of feeling is exceedingly striking in Euripides, for example, if compared with his predecessors, especially Æschylus; and yet Euripides was the favorite poet of his time. The same revolution is perceptible in the ancient historians. Horace, the poet of a cultivated and corrupt epoch, praises, under the shady groves of Tibur, the calm and happiness of the country, and he might be termed the true founder of this sentimental poetry, of which he has remained the unsurpassed model. In Propertius, Virgil, and others, we find also traces of this mode of feeling; less of it is found in Ovid, who would have required for that more abundance of heart, and who in his exile at Tomes sorrowfully regrets the happiness that Horace so readily dispensed with in his villa at Tibur. It is in the fundamental idea of poetry that the poet is everywhere the _guardian_ of nature. When he can no longer entirely fill this part, and has already in himself suffered the deleterious influence of arbitrary and factitious forms, or has had to struggle against this influence, he presents himself as the _witness_ of nature and as its avenger. The poet will, therefore, be the _expression_ of nature itself, or his part will be to _seek_ it, if men have lost sight of it. Hence arise two kinds of poetry, which embrace and exhaust the entire field of poetry. All poets—I mean those who are really so—will belong, according to the time when they flourish, according to the accidental circumstances that have influenced their education generally, and the different dispositions of mind through which they pass, will belong, I say, to the order of the _sentimental_ poetry or to _simple_ poetry.