The document discusses the structures and membership of the Catholic Church. It describes the hierarchical constitution of the Church including the Pope, bishops, priests, and deacons. It discusses the Episcopal College and the Pope's role as the visible head of the Church. It also describes the laity and consecrated religious life. The teaching, sanctifying, and governing offices of the bishops are summarized. The nature of Catholic unity is discussed as God calling all people to salvation through His one Church.