Multiple independent attestation means that a saying attributed to Jesus is attested in two or more independent sources—that is, sources that had no knowlege of one another. A saying found in Matthew, Mark and Luke, for example, is not independently attested since Matthew and Luke are dependent on Mark. On the other hand, a saying found in Mark and John, or Mark and Thomas, meets the standard of multiple independent attestation. This criterion is extremely important in historical Jesus research because it proves that a particular saying is earlier than any of the gospels in which it appears.