Pope Pius XII
Mystici Corporis Christi §20
Mystici Corporis Christi: On the Mystical Body of Christ
20 For the social needs of the Church Christ has provided in a particular way by the institution of two other Sacraments. Through Matrimony, in which the contracting parties are ministers of grace to each other, provision is made for the external and duly regulated increase of Christian society, and, what is of greater importance, for the correct religious education of the children, without which this Mystical Body would be in grave danger. Through Holy Orders men are set aside and consecrated to God, to offer the Sacrifice of the Eucharistic Victim, to nourish the flock of the faithful with the Bread of Angels and the food of doctrine, to guide them in the way of God's commandments and counsels and to strengthen them with all other supernatural helps.
Source: Mystici Corporis Christi (Vatican.va)