The gospels of Matthew, Mark, and Luke are referred to as the synoptic Gospels because they include many of the same stories, often in a similar sequence or identical wording. They stand in contrast to John, whose content is largely distinct. The question of their literary relationship—the synoptic problem—has been a topic of lively debate for centuries. The majority view says both Matthew and Luke have made direct use of the Gospel of Mark as a source while also drawing from an additional hypothetical set of notes, possibly even a personal diary of Jesus or one of the disciples, called Q.