"We current Justices read the Constitution in the only way that we can: as Twentieth Century Americans. We look to the history of the time of framing and to the intervening history of interpretation. But the ultimate question must be, what do the words of the text mean in our time. For the genius of the Constitution rests not in any static meaning it might have had in a world that is dead and gone, but in the adaptability of its great principles to cope with current problems and current needs."