Birth Name:  Giuseppe Melchiorre Sarto
Born: June 2, 1835 at Treviso, Italy
Died:  August 20, 1914 at the Vatican (Age 79)
Elected: August 4, 1903, the 257th Roman Pontiff
Canonized: May 29, 1954 by Pope Pius XII
Patron: Catechists
Pontificate:  Combated heresy of Modernism; Ordered all clergy to take oath against Modernism;  Lowered age of First Communion to age of reason; Encouraged frequent reception of the Eucharist; Commissioned the eventual 1917 Code of Canon Law;  Mandated catechism classes in every parish throughout the world;  Lit the fire that resulted in the Neo-Thomistic Movement of theology (Thomas Aquinas); Devoted to "Our Lady of Confidence"; issued motu propriu calling for "active participation" of the faithful at mass through liturgical reform;  Reformed the Roman curia;  Preferred an impoverished life as did his family in Italy;  Cooperated in at least two miracles while he was alive;  Beatified Joan of Arc.

 

Pascendi Domenici gregis (1907)

The most important encyclical issued by Pope St. Pius X was Pascendi Domenici gregis, which threw a harsh light on the growing heresy of Modernism in the Catholic Church.  The issue was so critical to Pius, only three years later he would require all clergy and seminarian educators to sign an oath against Modernism, or face penalties up to and including excommunication (see below).  The impact of this encyclical on the Church - especially in the past 50 years - is difficult to overstate.  In many ways, it has become a battle line drawn between Catholics who have been deeply impacted by the almost iconoclastic approach to Tradition after Vatican II, and those Catholics who believe Tradition is an obstacle to the mission of the Church going forward.  Like all things, the truth is in the middle.  Modernism, in short, doubts the relevance of the Deposit of Faith as a static foundation.  The oath, therefore, was intended to reassert, forcefully, that anything working against the Deposit is "the synthesis of all heresies".  
 

The Oath Against Modernism (1910) 

Pope St. Pius X composed the following oath to be sworn by clergy and seminarian professors under pain of excommunication.  The oath was rescinded by the Congregation for the Doctrine of the Faith in 1967, with the approval of Pope St. Paul VI.  The oath is an important document in Church history, and although it seems controversial today, we cannot help but be sobered by the gravity with which the pope carried out this decree.  
 

To be sworn to by all clergy, pastors, confessors, preachers, religious superiors, and professors in philosophical-theological seminaries.

I . . . . firmly embrace and accept each and every definition that has been set forth and declared by the unerring teaching authority of the Church, especially those principal truths which are directly opposed to the errors of this day. And first of all, I profess that God, the origin and end of all things, can be known with certainty by the natural light of reason from the created world (see Rom. 1:19), that is, from the visible works of creation, as a cause from its effects, and that, therefore, his existence can also be demonstrated: Secondly, I accept and acknowledge the external proofs of revelation, that is, divine acts and especially miracles and prophecies as the surest signs of the divine origin of the Christian religion and I hold that these same proofs are well adapted to the understanding of all eras and all men, even of this time. Thirdly, I believe with equally firm faith that the Church, the guardian and teacher of the revealed word, was personally instituted by the real and historical Christ when he lived among us, and that the Church was built upon Peter, the prince of the apostolic hierarchy, and his successors for the duration of time. Fourthly, I sincerely hold that the doctrine of faith was handed down to us from the apostles through the orthodox Fathers in exactly the same meaning and always in the same purport. Therefore, I entirely reject the heretical’ misrepresentation that dogmas evolve and change from one meaning to another different from the one which the Church held previously. I also condemn every error according to which, in place of the divine deposit which has been given to the spouse of Christ to be carefully guarded by her, there is put a philosophical figment or product of a human conscience that has gradually been developed by human effort and will continue to develop indefinitely. Fifthly, I hold with certainty and sincerely confess that faith is not a blind sentiment of religion welling up from the depths of the subconscious under the impulse of the heart and the motion of a will trained to morality; but faith is a genuine assent of the intellect to truth received by hearing from an external source. By this assent, because of the authority of the supremely truthful God, we believe to be true that which has been revealed and attested to by a personal God, our creator and lord.

Furthermore, with due reverence, I submit and adhere with my whole heart to the condemnations, declarations, and all the prescripts contained in the encyclical Pascendi and in the decree Lamentabili,especially those concerning what is known as the history of dogmas. I also reject the error of those who say that the faith held by the Church can contradict history, and that Catholic dogmas, in the sense in which they are now understood, are irreconcilable with a more realistic view of the origins of the Christian religion. I also condemn and reject the opinion of those who say that a well-educated Christian assumes a dual personality-that of a believer and at the same time of a historian, as if it were permissible for a historian to hold things that contradict the faith of the believer, or to establish premises which, provided there be no direct denial of dogmas, would lead to the conclusion that dogmas are either false or doubtful. Likewise, I reject that method of judging and interpreting Sacred Scripture which, departing from the tradition of the Church, the analogy of faith, and the norms of the Apostolic See, embraces the misrepresentations of the rationalists and with no prudence or restraint adopts textual criticism as the one and supreme norm. Furthermore, I reject the opinion of those who hold that a professor lecturing or writing on a historico-theological subject should first put aside any preconceived opinion about the supernatural origin of Catholic tradition or about the divine promise of help to preserve all revealed truth forever; and that they should then interpret the writings of each of the Fathers solely by scientific principles, excluding all sacred authority, and with the same liberty of judgment that is common in the investigation of all ordinary historical documents.

Finally, I declare that I am completely opposed to the error of the modernists who hold that there is nothing divine in sacred tradition; or what is far worse, say that there is, but in a pantheistic sense, with the result that there would remain nothing but this plain simple fact-one to be put on a par with the ordinary facts of history-the fact, namely, that a group of men by their own labor, skill, and talent have continued through subsequent ages a school begun by Christ and his apostles. I firmly hold, then, and shall hold to my dying breath the belief of the Fathers in the charism of truth, which certainly is, was, and always will be in the succession of the episcopacy from the apostles. The purpose of this is, then, not that dogma may be tailored according to what seems better and more suited to the culture of each age; rather, that the absolute and immutable truth preached by the apostles from the beginning may never be believed to be different, may never be understood in any other way.

I promise that I shall keep all these articles faithfully, entirely, and sincerely, and guard them inviolate, in no way deviating from them in teaching or in any way in word or in writing. Thus I promise, this I swear, so help me God.