A poet who is also a Platonist is likely to exalt his office; it is his not merely to amuse or to please, but to lead mankind nearer to the eternal ideal--Shelley called it Intellectual Beauty--which is the only abiding reality. This is the real theme of his 'Defence of Poetry' (1821), the best piece of prose he ever wrote. Thomas Love Peacock, scholar, novelist, and poet, and, in spite of his mellow worldliness, one of Shelley's most admired friends, had published a wittily perverse and paradoxical article, not without much good sense, on 'The Four Ages of Poetry'. Peacock maintained that genuine poetry is only possible in half-civilised times, such as the Homeric or Elizabethan ages, which, after the interval of a learned period, like that of Pope in England, are inevitably succeeded by a sham return to nature. What he had in mind was, of course, the movement represented by Wordsworth, Southey, and Coleridge, the romantic poets of the Lake School, whom he describes as a "modern-antique compound of frippery and barbarism." He must have greatly enjoyed writing such a paragraph as this: "A poet in our times is a semi-barbarian in a civilised community. ... The march of his intellect is like that of a crab, backward. The brighter the light diffused around him by the progress of reason, the thicker is the darkness of antiquated barbarism in which he buries himself like a mole, to throw up the barren hillocks of his Cimmerian labours." These gay shafts had at any rate the merit of stinging Shelley to action. 'The Defence of Poetry' was his reply. People like Peacock treat poetry, and art generally, as an adventitious seasoning of life--ornamental perhaps, but rather out of place in a progressive and practical age. Shelley undermines the whole position by asserting that poetry--a name which includes for him all serious art--is the very stuff out of which all that is valuable and real in life is made. "A poem is the very image of life expressed in its eternal truth." "The great secret of morals is love, or a going out of our own nature, and an identification of ourselves with the beautiful that exists in thought, action, or person, not our own. A man, to be greatly good, must imagine intensely and comprehensively; he must put himself in the place of another and of many others; the pains and pleasures of his species must become his own. The great instrument of moral good is the imagination." And it is on the imagination that poetry works, strengthening it as exercises strengthen a limb. Historically, he argues, good poetry always coexists with good morals; for instance, when social life decays, drama decays. Peacock had said that reasoners and mechanical inventors are more useful than poets. The reply is that, left to themselves, they simply make the world worse, while it is poets and "poetical philosophers" who produce "true utility," or pleasure in the highest sense. Without poetry, the progress