On the higher and more abstract questions of poetry (which are by no means to be neglected) Aristotle is the guide; but the meaning of Aristotle is not always self-evident even so far as it goes, and it sometimes requires supplementing. Poetry is the imitation of nature: but this imitation may be carried on either by copying nature as it is or by inventing things which do not actually exist, and have never actually existed, but which conduct themselves according to the laws of nature and reason. The poet is _not_ a public nuisance, but quite the contrary. He must, however, both delight _and_ instruct. As for the Kinds of poetry, they are not mere working classifications of the practice of poets, but have technically constituting definitions from which they might be independently developed, and according to which they ought to be composed. The general laws of Tragedy are given by Aristotle; but it is necessary to extend his prescription of Unity so as to enjoin three species—of Action, Time, and Place. Tragedy must be written in verse, which, though not exactly the constituting form of poetry generally, is almost or quite inseparable from it. The illegitimacy of prose in Comedy is less positive. Certain extensions of the rules of the older Epic may be admitted, so as to constitute a new Epic or Heroic Poem; but it is questionable whether this may have the full liberty of Romance, and it is subject to Unity, though not to the dramatic Unity. Other Kinds are inferior to these. In practising them, and in practising all, the poet is to look first, midmost, and last to the practice of the ancients. “The ancients” may even occasionally be contracted to little more than Virgil; they may be extended to take in Homer, or may be construed much more widely. But taking things on the whole, “the ancients” have anticipated almost everything, and in everything that they have anticipated have done so well that the best chance of success is simply to imitate them. The detailed precepts of Horace are never to be neglected; if supplemented, they must be supplemented in the same sense.