When a writer calls his work a Romance, it need hardly be observed that he wishes to claim a certain latitude, both as to its fashion and material, which he would not have felt himself entitled to assume, had he professed to be writing a novel. The latter form of composition is presumed to aim at a very minute fidelity, not merely to the possible, but to the probable and ordinary course of mans experience. The former - while, as a work of art, it must rigidly subject itself to laws, and while it sins unpardonably so far as it may swerve aside from the truth of the human heart - has fairly a right to present that truth under circumstances, to a great extent of the writers own choosing or creation. If he thinks fit, also, he may so manage his atmospherical medium as to bring out or mellow the lights, and deepen and enrich the shadows of the picture, he will be wise, no doubt, to make a very moderate use of the privilege here stated, and especially to mingle the marvellous rather as a slight, delicate and evanescent flavour, than as any portion of the actual substance of the dish offered to the public. He can hardly be said, however, to commit a literary crime, even if he disregarded this caution.
(Preface to The House of Seven Gables, 1851; quoted in Patrick Sheeran, The Novels of Liam OFlaherty: A Study in Romantic Realism [ Ph.D. Diss.] UCG 1972, p.160-69.)