Using the BCP, we are assured that our prayers speak with the voice of the whole church, and aren't simply the whim and desire of the individual priest. We speak on behalf of the church, after all, and not from the sinfulness or agenda of our own hearts.
The BCP allows us to read or chant many of the prayers from the text directly. There are times, however, when I have found it good to have certain prayers memorized. Mostly this is for pastoral reasons, when the need to make eye contact or appropriate gesture would make it difficult to be staring down into a book.
Here are the prayers that I have memorized, or am working on memorizing:
- The Collect for Purity "Almighty God, to you all hearts are open..." (which I pray facing the altar, in orans)
- Absolution at the end of General Confession "Almighty God have mercy..." BCP p. 360
- The "Standard" blessing at the end of Holy Eucharist (required in Rite I, optional but typical in Rite II) "The peace of God which passeth all understanding..." BCP p. 339. Note that the Book of Occasional Services contains seasonal blessings and Lenten prayers over the people.
- I discovered during CPE that I needed to memorize these two prayers from ministry at the time of death, found on pp. 464-5: The prayer called the Profiscere: "Depart, O Christian soul, out of this world..." and the Commedatory Prayer: "Into your hands, O merciful Savior..."
- Also, if you do a healing liturgy, you would benefit from memorizing whatever prayer you will pray while laying hands on a person or anointing them.
Anything else, other learned clergy?