The high levels of commonality between the first three Gospels have lead scholars to believe that there was a lost source which they call the Q document (from the German word "Quelle" "source"). Scholars believe that Matthew and Luke each had a copy of Mark and the Q document as their primary sources. Analysis of the 230 verses common to Matthew and Luke which are believed to make up this lost Q document reveal that it was mostly a list of sayings and parables of Jesus and not a narrative history of events in Jesus' life. The discovery of the Gospel of Thomas in the Nag Hammadi Library and Oxyrhynchus Papyrus 654 (which may be a fragment of the same) show that such lists of sayings did exist in the church from early times.
Gospel Matthew Mark Luke Total Verses 1070 677 1150 Unique Tradition 330 (1/3) 70 (1/10) 520 (1/2) Twofold Tradition 170 (Mk) 170 (Mt) 230 (Mt) 230 (Lk) 50 (Lk) 50 (Mk) Threefold Tradition 350 350 350 Two+Three Tradition 520 (5/7 Mk) 520 (1/2 Mt) 580 (1/2 Mt) 580 (1/2 Lk) 400 (1/3 Lk) 400 (4/7 Mk)