By Brian Resnick Now an American icon, the Huckleberry Finn author received his first big break in the pages of this magazine   Over its 154 years, the pages of The Atlantic have hosted essays and commentaries from literary luminaries such as Harriet Beecher Stowe, Walt Whitman, Arthur Miller, and Saul Bellow. But perhaps most culturally salient of them all is Mark Twain. Required reading for nearly all school children, Twain’s works are inextricably linked to American history. Today, on what would be Twain’s 176th birthday, his name and his work are still provocative. At the time of its publication, his most famous book, The Adventures of Huckleberry Finn, was a poignant satire of the South set against…