The first prayer, made with the hand and the voice together.
The name of the Trinity, spoken while tracing the Cross over the body.
When: At the beginning and end of every prayer, on waking, before meals, and when entering a church with holy water.
Why: It says in one gesture what we believe (one God in three Persons) and how we were saved (by the Cross). It is the sign we were marked with at Baptism.
In the name of the Father, and of the Son, and of the Holy Spirit. Amen.