They were best friends. They were collaborators, literary gadflies, and champions of the common people. They were the leading lights of the Harlem Renaissance. Zora Neale Hurston, the author of Their Eyes Were Watching God, and Langston Hughes, the author of "The Negro Speaks of Rivers" and "Let America Be America Again," first met in 1925, at a great gathering of black and white literati, and they fascinated each other. They traveled together...