When a priest celebrates Mass ad orientem, for certain parts he faces toward “liturgical east,” which is toward the altar with his back to the congregation. This is the practice in the Extraordinary Form of the Mass. Versus populum, or toward the people, is the practical norm in the Ordinary Form.
In an interview with the French Catholic magazine Famille Chrétienne, Cardinal Sarah pointed out that Vatican II did not require the priest to face the people for the whole Mass. And while it is appropriate for readers to face the congregation, the situation is different for parts of the Mass in which the priest and congregation are directly addressing God.
“[A]s soon as we reach the moment when one addresses God – from the Offertory onwards – it is essential that the priest and faithful look together towards the east. This corresponds exactly to what the Council Fathers wanted.”
To priests who think they are required to celebrate Mass facing the people, Cardinal Sarah says that celebrating Mass ad orientem is allowed without special permission.
“It is legitimate and complies with the letter and spirit of the Council. As prefect of the Congregation for Divine Worship and the Discipline of the Sacraments, I wish to recall that the celebration ad orientem is authorized by the rubrics, which specify the times when the celebrant must turn to the people.
“It is therefore not necessary to have special permission to celebrate facing the Lord.”