Today, Celeste and John delve into the Bernie Sanders phenomenon and what it means for the future of Democratic and third-party politics. Former Vermont Gov. Howard Dean, a supporter of Sanders rival Hillary Clinton, looks at the election through the lens of his own experiences as a 2004 presidential contender. He gives his take on not only Clinton and Sanders, but on presumptive GOP nominee Donald Trump as well. Providing an international perspective: Writer Sam Knight, who uses the knowledge he gained from producing a deeply reported New Yorker magazine profile of Labour leader Jeremy Corbyn to compare the state of left-flank politics in the U.S. and the U.K.