As the Middle Ages progressed, certain issues remained unresolved. Second to none in terms of its importance to the medieval church was the question of the pope's authority. During the fourteenth and fifteenth centuries, the papal office faced unique challenges from secular authorities, from rival popes, and from clergy who sought to consolidate the church's power within ecumenical councils. As different popes succumbed to and overcame these challenges, the papacy found itself sometimes losing ground, sometimes gaining ground, and always adapting to new realities within the church and society.