A short expression of praise to the Trinity from the very early Church. The first part appears to be from a baptismal formula and the second part was added as an anti-Arian statement. It is used extensively in the Divine Office and also many other devotions such as the Rosary.

Gloria Patri, et Filio, et Spiritui Sancto. Sicut erat in principio, et nunc, et semper, et in saecula saeculorum. Amen.

Glory be to the Father, and to the Son, and to the Holy Spirit. As it was in the beginning, is now, and will be forever. Amen.