The gospels are not always independent of each other. Matthew and Luke, for example, are likely dependent on Mark. The "criterion of multiple attestation" focuses on the sayings or deeds of Jesus that are attested to in more than one independent literary source such as Apostle Paul, Josephus, Q and/or the Gospel of the Hebrews. The force of this criterion is increased if a given motif or theme is also found in different literary forms such as parables, dispute stories, miracle stories, prophecy, and/or aphorism.