The following is an English translation, in part, of the Papal Bull, QUO PRIMUM, issued by Pope Saint Pius V in 1570. This solemn pronouncement restored the Holy Sacrifice of the Mass to its historic form, which dated from the early centuries of the Church, and preserved it forever by binding priests of the Latin Rite to an unchangeable form of the Divine Liturgy.

Quo Primum was the result of the formal proclamations of the Counci of Trent (1545-1563), the greatest dogmatic council in the history of the Catholic Church, which was convoked to examine and condemn the heresies of Luther and other Protestant "reformers"; to formulate a complete and uniform catechism to fully explain the Christian Faith and adequately instruct the people; to establish and regulate seminaries for the training of good priests; and to codify and preserve the Holy Mass.

The Council of Trent lasted 18 years and was presided over by five Popes, namely, Paul III, Julius III, Marcellus II, Paul IV and Pius IV. Of all the general councils, it lasted longest, issued the largest number of dogmatic and reformatory decrees, and produced the most beneficial results.

It should be noted that Pope Saint Pius V (1566-1572), author of Quo Primum, has been universally regarded as one of the greatest popes, and that he and Pope Saint Pius X (1903-1914) ("The Foe of Modernism") are the only two popes in the past 700 years who have been declared saints by canonical decrees of the Catholic Church.

Excerpts from Quo Primum
the Papal Bull of Pope St. Pius V
July, 1570

"From the very first, upon Our elevation to the chief Apostleship, We gladly turned Our mind and energies, and directed all Our thoughts, to those matters which concerned the preserving of a pure liturgy, and We strove, with God's help, by every means in Our power to accomplish this purpose. for, besides other decrees of the sacred Council of Trent, there were stipulations for Us to revise and re-edit the sacred books, the Catechism, the Missal, and the Breviary. Now that, God willing, the Catechism had been published for the instruction of the faithful, and that the Breviary has been thoroughly revised for the worthy praise of God, so that the Missal and Breviary are in harmony, as is fitting and proper -- for it is most becoming the in the Church there be only one proper manner of reciting the Psalms and only one rite for the celebration of Mass -- we deemed it necessary to give our immediate attention to what still remained to be done, namely, to re-edit the Missal as soon as possible."

"Wherefore, We decided to entrust this work to learned men We selected. These men then very carefully collated all their work with ancient codices in Our Vatican Library, and with reliable, incorrupt or emended codices from elsewhere. Besides this, they consulted the works of ancient and approved authors concerning the same sacred rites, and thus, have restored the Missal itself to the original form and rite of the holy Fathers. When this work had been reviewed numerous times and further emended, and after serious study and reflection, We commanded that it be printed without delay so that all might derive the benefits of this work, and thus priests would know which prayers to use and which rites and ceremonies they were required to observe in the future celebration of the Mass."

"Let all everywhere adopt and observe what has been handed down by the Holy Roman church, the mother and teacher of the other churches, and let not Masses be sung or read according to any other rite other than that of the Missal published by Us. This ordinance applies henceforth, now and forever, throughout all provinces of the Christian world, to all patriarchates. cathedral churches...in accord with the rites and customs of the Roman Church. This Missal is to be used by all churches...."

"Only this new rite is to be used, unless approval of the practice of saying Mass differently was given at the very time of the institution and confirmation of the church by the Apostolic See at least 200 years ago... in which cases We in no wise rescind their above-mentioned prerogative or custom. Accordingly, if this Missal, which We have seen fit to publish, be more agreeable to these latter, We grant them permission to celebrate Masses according to this Missal ...."

"However, all of the other aforementioned churches are hereby denied the use of other missals, which are to be discontinued entirely and absolutely; whereas by this present constitution, henceforth valid in perpetuity, We order and enjoin that this, Our recently published Missal, must never have anything added to it, that nothing be omitted from it, and that nothing whatsoever be changed in it -- under penalty of Our indignation."

"Wherefore, We specifically command each and every patriarch, administrator, and all other persons of what ever ecclesiastical dignity they may be ... and we order them in virtue of holy obedience to chant or to read the Mass according to the rite and manner and norm herewith laid down by Us ...and they must not, in celebrating Mass, presume to introduce any ceremonies or recite any prayers other than those contained in this Missal."

"Furthermore, by these presents, in virtue of Our Apostolic authority, We grant and concede in perpetuity that for the chanting or reading of the Mass in any church whatsoever, this Missal is hereafter to be followed absolutely, without any scruples of conscience or fear of incurring any penalty, judgement, or censure ...."

"We likewise declare and ordain that no one whatsoever is to be forced or coerced to alter this Missal, and that this present document cannot be revoked or modified, but remain always valid and retain its full force ...."

"Therefore, no one whosoever is permitted to alter this letter .... Should anyone, however, presume to commit such an act, he should know that he will incur the indignation of Almighty God and of the blessed Apostles Peter and Paul"

"given at St. Peter's in the year of the Lord's Incarnation, 1570, on the 19th day of July in the Fifth year of our Pontificate."