A Swahili (East and Central
Africa) riddle goes like this: 

      "I have a
riddle."

            "Let it come."

            "I shot my arrow without feathers; it has
returned with feathers?"

            (answer) "Runner bean." 

In its cultural context this African riddle has
two levels.  First is the literal meaning of the words: the example of an arrow
being shot.  The second level is the example from the farming cycle.  The seed
of the runner bean (a common type of bean) is first planted alone and
naked.   Then it grows into a shrub bearing runner beans.  So the once naked
(featherless) bean returns as a leafy shrub (with feathers), a symbol of
fruitfulness.

The
missionary parallel is the God the Father sending the Son to redeem humankind. 
There is a close similarity to Isaiah 55:11: "So shall my word be that
goes out from my mouth; it shall not return to me empty, but it shall accomplish
that which I purpose, and succeed in the thing for which I sent it." Then there
are the eloquent words of St. Paul’s "kenosis" passage in Philippians
2:6-9.