The first reading tells us that God sends us helpful ideas, and he sends us the strength to accomplish what we must. The reading compares those graces from God to the rain God sends down making the earth fruitful.
Our passage today is verses 10 and 11 from Isaiah Fifty-Five. They constitute the second half of four verses that make up a beautiful Bible poem. If we begin with verses 8 and 9, the complete poem reads:
8. My thoughts are not your thoughts, nor are your ways my ways, says the Lord. 9 As high as the heavens are above the earth, so high are my ways above your ways, and my thoughts above yo9ur thoughts.
10 For just as from the heavens, the rain and snow come down and do not return there till they have watered the earth, making it fertile and fruitful; giving seed to him who sows, and bread to him who eats, 11 so shall my word be that goes forth from my mouth; It shall not return to me void, but shall do my will, achieving the end for which I sent it.
In teaching grade school classes, I would hold up a five dollar bill that would be the reward for the first person to flawlessly recite the whole passage from memory. It was fun watching them throw their heads back trying to chug-along the whole passage.