What is Prayer?

Prayer is a conversation of man with God.  

He who prays with a broken and humbled spirit is filled with divine gifts and blessings - that is, with joy, peace, comfort, illumination, and consolation - and he, too, becomes blessed.  Prayer is a doubled-edged sword that slays despair, saves from danger, assuages grief, and so on.  Prayer is a preventative medicine for all diseases of soul and body.

Elder Ephraim of Philotheou (Mt. Athos)

"The person found worthy of praising God gains more by it than God, for he has received a great and marvelous gift of grace. The more he praises God, the more he becomes a debtor, until finally he finds no limit or interruption to his knowledge of God or to thanksgiving or humility or love."

St. Peter of Damascus 

"Where humility is combined with the remembrance of God that is established through watchfulness and attention, and also with recurrent prayer inflexible in its resistance to the enemy, there is the place of God, the heaven of the heart in which because of God's presence no demonic army dares to make a stand."

St. Philotheos of Sinai