Tertullian gives us the essentials on prayer. Starting with the Lord's Prayer, he breaks down each section, giving us expounded meaning into each phrase. He then goes on to discuss where and when we should pray, how we should pray and what the importance of prayer is in our faith life.

"But how far more amply operative is Christian prayer! It does not station the angel of dew in mid-fires, nor muzzle lions, nor transfer to the hungry the rustics' bread; it has no delegated grace to avert any sense of suffering; but it supplies the suffering, and the feeling, and the grieving, with endurance: it amplifies grace by virtue, that faith may know what she obtains from the Lord, understanding what--for God's name's sake--she suffers."
-Tertullian