In the beginning of Isaiah 55 God invites His people to come to Him and fellowship with Him. In verses 3 and 6 God says,
"Incline your ear, and come to Me. Hear, and your soul shall live…. Seek the LORD while He may be found, call upon Him while He is near."
In verses 10-11, we are told what happens to those who respond to this invitation, to God's call to come and seek Him and listen to Him,
"For as the rain comes down, and the snow from heaven, and do not return there, but water the earth, and make it bring forth and bud, that it may give seed to the sower and bread to the eater, so shall My word be that goes forth from My mouth; it shall not return to Me void, but it shall accomplish what I please, and it shall prosper in the thing for which I sent it."
In the same way rain brings blessing when it waters the earth (causing it to bring a bountiful harvest and fruitfulness into the lives of the people), so God's spiritual influence brings refreshment and fruitfulness to our lives.
What is God's spiritual influence? It is the impact of His Word and His Spirit upon the hearts of His children.
When you come to God, when you respond to His call to seek Him and incline your ear, He will speak to you. And the effect His Word has when He speaks it into your life, into your heart, is the same effect that rain has on the earth.
His Word, as it penetrates your heart, will bring refreshment, enlightenment, and ultimately, fruitfulness. It will bring revival into your heart causing spiritual growth and progress.