31) Justin has the striking word [Greek: apodokimasthaenai], with Mark and Luke against Matthew, and [Greek: hupo] with Mark against the [Greek: apo] of the two other Synoptics.

This last coincidence can perhaps hardly be pressed, as [Greek: hupo] would be the more natural word to use.
In the cases where we have only the double synopsis to compare with Justin, we have no certain test to distinguish between the primary and secondary features in the text of the Gospels.

We cannot say with confidence what belonged to the original document and what to the later editor who reduced it to its present form.
In these cases therefore it is possible that when Justin has a detail that is found in St.Matthew and wanting in St.Luke, or found in St.Luke and wanting in St.Matthew, he is still not quoting directly from either of those Gospels, but from the common document on which they are based.

The triple synopsis however furnishes such a criterion.

It enables us to see what was the original text and how any single Evangelist has diverged from it.
Thus in the two instances quoted at the beginning of the last paragraph it is evident that the Lucan text represents a deviation from the original, and _that deviation Justin has reproduced_.