Chapter 21 — Part II: The Sacraments — Holy Orders
Section 24. Number of Orders — Now, to use the words of the holy Council: The ministry of so sublime a priesthood being a thing all divine, it is but befitting its worthier and more reverent exercise that in the Church's well-ordered disposition there should be several different orders of ministers destined to assist the priesthood by virtue of their office, -- orders arranged in such a way that those who have already received clerical tonsure should be raised, step by step, from the lower to the higher orders.