Textual criticism principle: the reading that explains the other readings is likely original

Mike illustrates the principle with the 'children/horses' example where one letter difference in Greek produced a scribal error. The principle states: whichever reading best explains the existence of the other readings is probably authentic. Applied here: the traditional placement best explains why one scribe moved the verses (he thought it flowed better after verse 40). The difficulty of the passage in its original location gives more reason to think it is authentic there.