"For as the rain and the snow come down from heaven,
And do not return there without watering the earth
And making it bear and sprout,
And furnishing seed to the sower and bread to the eater;
So will My word be which goes forth from My mouth;
It will not return to Me empty,
Without accomplishing what I desire,
And without succeeding in the matter for which I sent it."
God sends the life giving rain and snow to the earth for a purpose. Water is necessary for the cycle of life. Without it the seeds could not produce plants for food, nor return to seed again to repeat the cycle. Moisture eventually returns to the heavens, but not until it has accomplished its purpose on earth. So it is with God's word. He sends it forth with a purpose and it will not return to Him without first accomplishing what He desires. It never fails; it always succeeds.