In those species which have men and manners professedly for their theme, a strict conformity with human nature is reasonably demanded.
Non hic Centauros, non Gorgonas, Harpyiasque
Invenies: hominem pagina nostra sapit;
is a proper motto to a book of epigrams; but would make a poor figure at the head of an epic poem.
Still further in those species that address themselves to the heart, and would obtain their end, not through the imagination, but through the passions, there the liberty of transgressing nature, I mean the real powers and properties of human nature, is infinitely restrained; and poetical truth is, under these circumstances, almost as severe a thing as historical.
The reason is, we must first believe before we can be affected.
But the case is different with the more sublime and creative poetry. This species, addressing itself solely or principally to the Imagination; a young and credulous faculty, which loves to admire and to be deceived; has no need to observe those cautious rules of credibility, so necessary to be followed by him who would touch the affections and interest the heart.
This difference, you will say, is obvious enough: How came it then to be overlooked? From another mistake, in extending a particular precept of the drama into a general maxim.
The incredulus odi of Horace ran in the heads of these critics, though his own words confine the observation singly to the stage:
Segnius irritant animos demissa per aurem
Quam quæ sunt oculis subjecta fidelibus, et quæ
Ipse sibi tradit Spectator——
That, which passes in representation, and challenges, as it were, the scrutiny of the eye, must be truth itself, or something very nearly approaching to it. But what passes in narration, even on the stage, is admitted without much difficulty—