But Lowell's greatest contribution to the anti-slavery cause was the _Biglow Papers_, a series of satirical poems in the Yankee dialect, aimed at the politicians who were responsible for the Mexican War, a war undertaken, as he believed, in the interests of the Southern slaveholders. Hitherto the Abolitionists had been regarded with contempt by the conservative, complacent advocates of peace and "compromise," and to join them was essentially to lose caste in the best society. But now a laughing prophet had arisen whose tongue was tipped with fire. The _Biglow Papers_ was an unexpected blow to the slave power. Never before had humor been used directly as a weapon in political warfare. Soon the whole country was ringing with the homely phrases of Hosea Biglow's satiric humor, and deriding conservatism began to change countenance. "No speech, no plea, no appeal," says George William Curtis, "was comparable in popular and permanent effect with this pitiless tempest of fire and hail, in the form of wit, argument, satire, knowledge, insight, learning, common-sense, and patriotism. It was humor of the purest strain, but humor in deadly earnest." As an embodiment of the elemental Yankee character and speech it is a classic of final authority. Says Curtis, "Burns did not give to the Scotch tongue a nobler immortality than Lowell gave to the dialect of New England." The year 1848 was one of remarkably productive results for Lowell. Besides the _Biglow Papers_ and some forty magazine articles and poems, he published a third collection of _Poems_, the _Vision of Sir Launfal_, and the _Fable for Critics_. The various phases of his composite genius were nearly all represented in these volumes. The _Fable_ was a good-natured satire upon his fellow authors, in which he touched up in rollicking rhymed couplets the merits and weaknesses of each, not omitting himself, with witty characterization and acute critical judgment; and it is still read for its delicious humor and sterling criticism. For example, the lines on Poe will always be quoted: "There comes Poe, with his raven, like Barnaby Rudge, Three-fifths of him genius and two-fifths sheer fudge." And so the sketch of Hawthorne: "There is Hawthorne, with genius so shrinking and rare That you hardly at first see the strength that is there; A frame so robust, with a nature so sweet, So earnest, so graceful, so lithe and so fleet, Is worth a descent from Olympus to meet."