It’s been called the most exclusive club in the world, with membership limited to living ex-presidents and the current occupant of the Oval Office. On Thursday, Barack Obama is joining four of his predecessors—Jimmy Carter, Bill Clinton, and the two Bushes—for a reunion of that club, to mark the opening of the George W. Bush Presidential Center in Dallas. It is a rare moment for the country to savor, with all five coming together in the warm glow of friendship to underscore the special bond that exists among those who have held the presidency. They rarely speak ill of each other, at least not in public, and stand ready to respond like a troupe of superheroes in times of crisis.