Rather than look for an outside source (such as Q <ref>The Q document theory was created by Greek to try to understand why the gospels differ and why they are the same. They theorize that the gospel writers used a common text as their source. The gospek writers did not write in a vacuum, requiring a source text to copy from. Matthew has the book of Mark. Luke had Mark and Matthew, and John had the other three.</ref>) for Mark, perhaps a closer look at the scriptures available to Peter in is order.

Marks gospel was widely circulated. It became the core teaching of the gospel. With time, as the apostles learned to read the 'mystery which was hidden from the beginning' their gospel supplemented Mark with additional insights they had gained as they studied to show themselves approved.