When Helen Vendler was a graduate student in English in the 1950s at Harvard University she was barred from the school’s Lamont Library, where the poetry room was located, because she was a woman. Regardless, Vendler, who now holds an endowed chair at Harvard, went on to become one of the country’s most important poetry critics. Arion Press just published “Stone from Delphi,” an anthology of Seamus Heaney’s work selected by Vendler with an introduction by her.