Poetry is not the proper antithesis to prose, but to science. Poetry is opposed to science, and prose to metre. The proper and immediate object of science is the acquirement, or communication, of truth; the proper and immediate object of poetry is the communication of immediate pleasure. This definition is useful; but as it would include novels and other works of fiction, which yet we do not call poems, there must be some additional character by which poetry is not only divided from opposites, but likewise distinguished from disparate, though similar, modes of composition. Now how is this to be effected? In animated prose, the beauties of nature, and the passions and accidents of human nature, are often expressed in that natural language which the contemplation of them would suggest to a pure and benevolent mind; yet still neither we nor the writers call such a work a poem, though no work could deserve that name which did not include all this, together with something else. What is this? It is that pleasurable emotion, that peculiar state and degree of excitement, which arises in the poet himself in the act of composition;—and in order to understand this, we must combine a more than ordinary sympathy with the objects, emotions, or incidents contemplated by the poet, consequent on a more than common sensibility, with a more than ordinary activity of the mind in respect of the fancy and the imagination. Hence is produced a more vivid reflection of the truths of nature and of the human heart, united with a constant activity modifying and correcting these truths by that sort of pleasurable emotion, which the exertion of all our faculties gives in a certain degree; but which can only be felt in perfection under the full play of those powers of mind, which are spontaneous rather than voluntary, and in which the effort required bears no proportion to the activity enjoyed. This is the state which permits the production of a highly pleasurable whole, of which each part shall also communicate for itself a distinct and conscious pleasure; and hence arises the definition, which I trust is now intelligible, that poetry, or rather a poem, is a species of composition, opposed to science, as having intellectual pleasure for its object, and as attaining its end by the use of language natural to us in a state of excitement,—but distinguished from other species of composition, not excluded by the former criterion, by permitting a pleasure from the whole consistent with a consciousness of pleasure from the component parts;—and the perfection of which is, to communicate from each part the greatest immediate pleasure compatible with the largest sum of pleasure on the whole. This, of course, will vary with the different modes of poetry;—and that splendour of particular lines, which would be worthy of admiration in an impassioned elegy, or a short indignant satire, would be a blemish and proof of vile taste in a tragedy or an epic poem.