2048 The precepts of the Church concern the moral and Christian life united with the liturgy and nourished by it. 2049 The Magisterium of the Pastors of the Church in moral matters is ordinarily exercised in catechesis and preaching, on the basis of the Decalogue which states the principles of moral l~fe valid for every man. 2050 The Roman Pontiff and the bishops, as authentic teachers, preach to the People of God the faith which is to be believed and applied in moral l~fe. It is also incumbent on them to pronounce on moral questions that fall within the natural law and reason. 2051 The infallibility of the Magisterium of the Pastors extends to all the elements of doctrine, including moral doctrine, without which the saving truths of the faith cannot be preserved, expounded or observed.