There is a sign on the sacristy wall of St. Elizabeth Ann Seton Basilica in Emmitsburg, Md., which reads, “Priest of God, celebrate this Mass as if it were your first Mass, your last Mass, your only Mass.” It is a potent reminder to the priest to pay attention to what he is doing. He is not to celebrate the sacred mysteries with a careless or cavalier attitude, but with the proper reverence and disposition. He is not at the altar to entertain or improvise, nor should he rush through the Mass as quickly as possible. He is a priest,...