The First Dogmatic Constitution on the Church of Christ, approved in the fourth session of the First Vatican Council. Its four chapters define that Christ instituted the apostolic primacy in Saint Peter; that this primacy endures by Christ's own institution in the Roman Pontiffs, Peter's successors; that the Roman Pontiff's power is a primacy of true, ordinary and immediate episcopal jurisdiction over the whole Church and over each of the faithful, which does not diminish but supports the ordinary jurisdiction of the bishops in their own sees; and that when he speaks ex cathedra — that is, when as pastor and teacher of all Christians he defines by his supreme apostolic authority a doctrine concerning faith or morals to be held by the whole Church — he possesses that infallibility with which Christ willed his Church to be endowed. The Council was suspended before it could complete its treatment of the Church; that work was taken up by Lumen Gentium.