Catechism of the Catholic Church

Intrinsically linked to the sacramental nature of ecclesial ministry is its character as service. Entirely dependent on Christ who gives mission and authority, ministers are truly "slaves of Christ," in the image of him who freely took "the form of a slave" for us. Because the word and grace of which they are ministers are not their own, but are given to them by Christ for the sake of others, they must freely become the slaves of all. (1551, 427)