From 1666 to 1774 most of the 'Epistles' were written; and also his best known work, 'L'Art poétique' (The Art of Poetry). In the satires he had been destructive, but he was too practical to be negative. The 'Art of Poetry,' modeled after Horace's work of that name, offers the theory of poetic composition. It is a work in four cantos of couplets: the first setting forth general rules of metrical composition; the second a dissertation upon different forms--ode, sonnet, pastoral, and others; the third treating tragedy, comedy, and epic poetry; and the last consisting of general reflections and advice to authors. Briefly stated, Boileau's desire was to establish literature upon a foundation of unchanging laws. Why did some works speedily die while others endure through the centuries? Because works akin to the eternal classics did not, like much contemporary writing, reflect the trivial and evanescent. They contained what is perennially true of humanity; and stated this in a simple, interesting, and reasonable way. Above all, Boileau demands truth in subject, and the conscientious workmanship which finds the most suitable form of expression. To see a word at the end of a couplet only because it rhymes with the word above it, he finds inexcusable. Without a method resulting in unity, clearness, and proportion, writing is not literature. Later, in his 'Reflections upon Longinus,' Boileau repeated and emphasized these views. His mock-heroic poem 'Le Lutrin' (The Reading-Desk), ridiculing clerical pettinesses, was strong in realistic descriptions, and was perhaps his most popular work. A modern poet's definition of poetry as "the heat and height of sane emotion" would have been unintelligible to Boileau. Deficient in imagination, he always saw life on its material side, and was irritated by any display of emotion not reducible to logic. So his poetry is sensible, clear argument in exquisitely careful metre. His great strength lay in a taste which recognized harmony and fitness instinctively. To us his quality is best translated by the dainty, perfect couplets of his imitator Pope. His talent, essentially French in its love of effect and classification, has strewn the language with clever saws, and his works have been studied as authoritative models by generation after generation of students.