Under the newly adopted canons of French taste, narrative and didactic verse, or satire, took first place. Blank verse was tabooed as too prose-like; so, too, were the enjambed rhymes. A succession of rhymed pentameter couplets, with the sense complete in each couplet, was set forth as the proper vehicle for poetry; and this unenjambed distich fettered English verse for three-quarters of a century. In the drama the characters must be noble, the language dignified; the metrical form must be the rhymed couplet, and the unities of time, place, and action must be observed. Such, in brief, were the principles of French Classicism as applied to English poetry, principles of which Dryden was the first great exponent, and which Pope in the next generation carried to absolute perfection. Waller, Marvell, and Cowley all tried their pens in the new method, Cowley with least success; and they were the poets in vogue when Dryden himself first attracted attention. Denham quite caught the favor of the critics with his mild conventionalities; the Earl of Roscommon delighted them with his rhymed _Essay on Translated Verse_; the brilliant court wits, Rochester, Dorset, and Sedley, who were writing for pleasure and not for publication, still clung to the frivolous lyric; but the most-read and worst-treated poet of the Restoration was Butler. He published his _Hudibras_, a sharp satire on the extreme Puritans, in 1663. Every one read the book, laughed uproariously, and left the author to starve in a garret. Of Dryden's contemporaries in prose, there were Sir William Temple, later the patron of Swift, John Locke who contributed to philosophy his _Essay Concerning the Human Understanding_, the two diarists Evelyn and Pepys, and the critics Rymer and Langbaine; there was Isaac Newton, who expounded in his _Principia_, 1687, the laws of gravitation; and there was the preaching tinker, who, confined in Bedford jail, gave to the world in 1678 one of its greatest allegories, _Pilgrim's Progress_. Dryden was nearly thirty before the production of the drama was resumed in England. Parliament had closed the theaters in 1642, and that was an extinguisher of dramatic genius. Davenant had vainly tried to elude the law, and finally succeeded in evading it by setting his _Siege of Rhodes_ to music, and producing the first English opera. At the Restoration, when the theaters were reopened, the dramas then produced reflected most vividly the looseness and immorality of the times. Their worst feature was that "they possessed not wit enough to keep the mass of moral putrefaction sweet."