On the Catholic Priesthood
A Priest Forever!
It is significant that Holy Orders is one of the three Sacraments that impress an indelible seal or mark on the soul,
called character. It implies a special consecration to almighty God, and is a reminder that the person thus sealed
or marked should walk worthy of the character he bears, either as a child, a soldier, and, above all, a priest of the true God.
Once a priest, a priest forever, whether he tread in the footsteps of John and Augustine, or of Judas and Arius.
Source: A Pulpit Commentary on Catholic Teaching: The liturgy of the ecclesiastical year