51 It is not Our intention at this time to enter upon a lengthy treatment of the Church's teaching on the priesthood and on the Eucharistic Sacrifice as it has been handed down from antiquity. Our predecessors Pius XI and Pius XII have done this in clear and important documents and We urge you to take pains to see to it that the priests and faithful entrusted to your care are very familiar with them. This will clear up the doubts of some; and correct the more daring statements that have sometimes been made in discussing these matters.
Source: Sacerdotii Nostri Primordia (Vatican.va)