The following line of "Blackberry-Picking" features a reference to one of history's most renowned and lethal pirates: Bluebeard. In this line, Heaney expands on the metaphor of summer's blood. The berries are like blackberries - which are abundant in Northern Ireland during this time of year. Additionally, he refers to blueberries as well - since they are also common here. Finally, Heaney calls them "virgin" berries because they have never been harvested before. Here is how the poem begins: "Blackberry-picking," she said, "I'll give you a box to carry." So she took him down to the cellar where the boxes were kept and opened one of them. Inside was a white dress with blue stripes and a yellow flower embroidered on it. "This is for you," her mother said. "Now go back out there and play your part." Heaney ends the poem by saying that the girl "went along without asking questions". This shows that she was probably not very old. Otherwise, she would have asked why their mother didn't want them to meet until after she was married. As for Bluebeard himself, he was a violent man who murdered several wives.