empire of chimeras

Horace was not one of these who believe that the caprice of the poet suffers no law above itself. In modern times, Young sounded the tocsin of Pseudo-Romanticism, when he declared that “in the fairy-land of fancy genius may wander wild; there it has a creative power, and may reign arbitrarily over its own empire of chimeras.” The poet, indeed, can create a world of his own, and, if he is endowed with the true genius of the poet, can insure our belief in his creation. But, even the poet must not offend our sense of congruity by endeavouring to unite things that are essentially incompatible. Horace would have no sympathy with the false Romanticism which could bring into being a world of chimeras having no conceivable relation with existing experience. Such things he would regard as the fevered dreams of a diseased imagination. He would thus look askance at the riot of imagination, and the unfettered play of emotion, which many regard as the divine prerogative of poets.
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In a later passage of the Ars Poetica, he seems to go still further, when he insists that the poet’s fictions be “proxima veris.” [435-436]

—J. F. D’Alton, Roman Literary Theory & Criticism (Russell & Russell, 1962)