The U2 frontman told the Penn graduates he used to think the future was solid, something you inherited like an old building. But he came to see it as malleable, waiting to be hammered into shape. He titled his speech 'Because We Can, We Must' and argued that their generation was the first that could look at extreme poverty and say with a straight face they could end it. The degree they were receiving, he said, was a blunt instrument — 'So go forth and build something with it.'