Sign of the Cross
Signum Crucis
Christians have traced the cross on themselves since the second century; Tertullian wrote that they marked their foreheads with it before every task. The words name the Trinity and the gesture recalls the Cross, so the whole faith is spoken in one breath. Catholics touch the forehead, the chest, then the left and right shoulder.
2nd-century practice; Matthew 28:19
In the name of the Father, and of the Son, and of the Holy Spirit.
Amen.