“Who was Samuel Greenberg?” editor Garrett Caples asks: “The short answer is ‘the dead, unknown poet Hart Crane plagiarized.’” In the winter of 1923, Crane was given some of Greenberg’s notebooks and called him “a Rimbaud in embryo.” Crane included many of Greenberg’s lines, uncredited and slightly changed, in his own poetry. Poems from the Greenberg Manuscript was edited by James Laughlin, who first published it in 1939. As well as Laughlin’s original essay, Caples includes a new selection of poems from Greenberg’s notebooks, along with some of his prose.…