Though in its beginnings prayer is so simple that even a small child can pray, it is at the same time the highest and holiest work to which anyone can rise. It is fellowship with the unseen and most holy One. The powers of the eternal world have been placed at its disposal. It is the very essence of true religion. It is the channel of all blessings and the secret of power and life. Through prayer, God has given to everyone the right to take hold of Him and His strength. It is on prayer that promises wait for their fulfillment, the kingdom for its coming, and glory of God for its full revelation.
Taken from the book Teach Me to Pray by Andrew Murray 1828-1917