Jesus and Paul seem to contradict with their children metaphors (don't be like a child / be like a child). We must distinguish the "big baby" from the "innocent child" images, denoting "immature" from and "humble" respectively. Christ had to puncture the prideful ego of several of His disciples who were parceling out the future positions of authority in the Kingdom. Christ warned that unless they changed their presumptuous attitude, assuming a more humble teachable demeanor as an unassuming child, they wouldn't even be in the Kingdom. As we return the physical leavening into our lives, we need to take on the stance of a trusting unassuming child (who will even forgive an undeserved punishment administered by a well-meaning but mistaken grandfather) to keep the spiritual leavening out of our lives.