The more prayer is in the world, the better the world will be, the mightier the forces against evil everywhere .
It is in one phase of its operation, a disinfectant and a preventive. It purifies the air; it destroys the contagion of evil. It is no fitful, short-lived thing. It is no voice crying unheard and unheeded in the silence. It is a voice which goes into God’s, and it lives as long as God’s ear is open to holy pleas, as long as God’s heart is alive to holy things. God shapes the world by it.
They are deathless. The lips that uttered them may be closed to death, the heart that felt them may have ceased to beat, but the they live before God, and God’s heart is set on them and they outlive the lives of those who uttered them; they outlive a generation, outlive an age, outlive a world. That man is the most immortal who has done the most and the best service of calling on God. They are God heroes, God’s saints, God’s servants, God’s vicegerents.
A man can seek God's face better because of calling on Him in the past; a man can live holier because of the waillings of the past; the man of many and acceptable moments of travail has done the truest and greatest service to the incoming generation. The times of calling on The King of kings strengthen the unborn generation against the desolating waves of sin and evil
With Christ in the School of Prayer by Andrew Murray