can only have one legacy held by only one man. two popes become a clear sign that the spiritual source of papal power has been abandoned. >> having two popes is impossible. it's shattering for christendom. reformers say we've got to do something about this. >> with the future of the church hanging in the balance, in 1415, cardinals on both sides look for a solution. >> they convene a general council at con stance, and the pope's involved are summoned and are either deposed or invited to resign. >> both the roman pope, gregory xii, and the avignon pope, benedict xii, are forced to resign.