According to the Orthodox tradition, the Lord’s Prayer is the key to all prayer.  Indeed, a careful survey of the great treasures of our Fathers on the subject of prayer indicates that all genuine prayers are related to the Lord’s Prayer, and that the latter represents a fullness which is not to be found elsewhere.  In the earliest manual of Church life and order, the Didache of the Twelve Apostles (1st c.), the recital of the Lord’s Prayer three times daily is mentioned as an obligation for the faithful.  This is reiterated in the seventh book of the Apostolic Constitutions (ch. 24), a later manual (3rd c.), which deals with “the manner of life of the Christians, the Divine Eucharist and Christian Initiation.”