Ad diem illum laetissimum: on the Immaculate Conception
3 September 2025
To celebrate the feast of St Pius X (3 September), we present this abridgement of his great 1904 encyclical on the Immaculate Conception of the Blessed Virgin Mary.
Our Predecessor Pius IX, Pontiff of holy memory, surrounded by a noble crown of Cardinals and Bishops, pronounced and promulgated with the authority of the infallible magisterium as a truth revealed by God that the Most Blessed Virgin Mary in the first instant of her conception was free from all stain of original sin. All the world knows the feelings with which the faithful of all the nations of the earth received this proclamation and the manifestations of public satisfaction and joy which greeted it, for truly there has not been in the memory of man any more universal or more harmonious expression of sentiment shown towards the august Mother of God or the Vicar of Jesus Christ.
Surely the Providence of God has shown itself admirable in Our two predecessors, Pius and Leo, who ruled the Church in most turbulent times with such great holiness through a length of Pontificate conceded to no other before them. Then, again, no sooner had Pius IX, proclaimed as a dogma of Catholic faith the exemption of Mary from the original stain, than the Virgin herself began in Lourdes those wonderful manifestations, followed by the vast and magnificent movements which have produced those two temples dedicated to the Immaculate Mother, where the prodigies which still continue to take place through her intercession furnish splendid arguments against the incredulity of our days.
[W]hy should we not believe that our salvation is nearer than we thought; all the more since we know from experience that, in the dispensation of Divine Providence, when evils reach their limit, deliverance is not far distant. “Her time is near at hand, and her days shall not be prolonged. For the Lord will have mercy on Jacob and will choose one out of Israel” (Is 14: 1). Wherefore the hope we cherish is not a vain one, that we, too, may before long repeat: “The Lord hath broken the staff of the wicked, the rod of the rulers. The whole earth is quiet and still, it is glad and hath rejoiced” (verses 5,7).
For can anyone fail to see that there is no surer or more direct road than by Mary for uniting all mankind in Christ and obtaining through Him the perfect adoption of sons, that we may be holy and immaculate in the sight of God? For if to Mary it was truly said: “Blessed art thou who hast believed because in thee shall be fulfilled the things that have been told thee by the Lord” (Lk 1:45); or in other words, that she would conceive and bring forth the Son of God and if she did receive in her breast Him who is by nature Truth itself in order that “He, generated in a new order and with a new nativity, though invisible in Himself, might become visible in our flesh”.
Hence whenever the Scriptures speak prophetically of the grace which was to appear among us, the Redeemer of mankind is almost invariably presented to us as united with His mother. The Lamb that is to rule the world will be sent — but He will be sent from the rock of the desert; the flower will blossom, but it will blossom from the root of Jesse. Adam, the father of mankind, looked to Mary crushing the serpent’s head, and he dried the tears that the malediction had brought into his eyes. Noah thought of her when shut up in the ark of safety, and Abraham when prevented from the slaying of his son; Jacob at the sight of the ladder on which angels ascended and descended; Moses amazed at the sight of the bush which burned but was not consumed; David escorting the ark of God with dancing and psalmody; Elias as he looked at the little cloud that rose out of the sea. In fine, after Christ, we find in Mary the end of the law and the fulfilment of the figures and oracles.
[T]hat through the Virgin, and through her more than through any other means, we have a way of reaching the knowledge of Jesus Christ, cannot be doubted when it is remembered that with her alone of all others Jesus was for thirty years united, as a son is usually united with a mother, in the closest ties of intimacy and domestic life. Who could better than His Mother have an open knowledge of the admirable mysteries of the birth and childhood of Christ, and above all of the mystery of the Incarnation, which is the beginning and the foundation of faith? Mary not only preserved and meditated on the events of Bethlehem and the facts which took place in Jerusalem in the Temple of the Lord but, sharing as she did the thoughts and the secret wishes of Christ, she may be said to have lived the very life of her Son. Hence nobody ever knew Christ so profoundly as she did, and nobody can ever be more competent as a guide and teacher of the knowledge of Christ.
Hence it follows, as We have already pointed out, that the Virgin is more powerful than all others as a means for uniting mankind with Christ. Hence too since, according to Christ Himself, “Now this is eternal life: That they may know thee the only truly God, and Jesus Christ whom thou hast sent” (Jn 17:3), and since it is through Mary that we attain to the knowledge of Christ, through Mary also we most easily obtain that life of which Christ is the source and origin.
It cannot, of course, be denied that the dispensation of these treasures is the particular and peculiar right of Jesus Christ, for they are the exclusive fruit of His Death, who by His nature is the Mediator between God and man. Nevertheless, by this companionship in sorrow and suffering already mentioned between the Mother and the Son, it has been allowed to the august Virgin to be the most powerful mediatrix and advocate of the whole world with her Divine Son. The source, then, is Jesus Christ “of whose fullness we have all received” (Jn 1:16), “from whom the whole body, being compacted and fitly joined together by what every joint supplieth, according to the operation in the measure of every part, maketh increase of the body unto the edifying of itself in charity” (Eph 4:16). But Mary, as St Bernard justly remarks, is the channel; or, if you will, the connecting portion the function of which is to join the body to the head and to transmit to the body the influences and volitions of the head. Yes, says St Bernardine of Sienna, “she is the neck of Our Head, by which He communicates to His mystical body all spiritual gifts”.
We are then, it will be seen, very far from attributing to the Mother of God a productive power of grace — a power which belongs to God alone. Yet, since Mary carries it over all in holiness and union with Jesus Christ, and has been associated by Jesus Christ in the work of redemption, she merits for us de congruo, in the language of theologians, what Jesus Christ merits for us de condigno, and she is the supreme Minister of the distribution of graces. Jesus “sitteth on the right hand of the majesty on high” (Heb 1). Mary sitteth at the right hand of her Son — a refuge so secure and a help so trusty against all dangers that we have nothing to fear or to despair of under her guidance, her patronage, her protection.
[There are t]hose, alas! who seduced by the wiles of the demon or deceived by false doctrines think they can do without the help of the Virgin. Hapless are they who neglect Mary under pretext of the honour to be paid to Jesus Christ! As if the Child could be found elsewhere than with the Mother!
Let then crowds fill the churches — let solemn feasts be celebrated and public rejoicings be made: these are things eminently suited for enlivening our faith. But unless heart and will be added, they will all be empty forms, mere appearances of piety. At such a spectacle, the Virgin, borrowing the words of Jesus Christ, would address us with the just reproach: “This people honoureth me with their lips, but their heart is far from me” (Mt 15:8).
For to be right and good, worship of the Mother of God ought to spring from the heart; acts of the body have here neither utility nor value if the acts of the soul have no part in them. Now these latter can only have one object, which is that we should fully carry out what the divine Son of Mary commands. For if true love alone has the power to unite the wills of men, it is of the first necessity that we should have one will with Mary to serve Jesus our Lord. What this most prudent Virgin said to the servants at the marriage feast of Cana she addresses also to us: “Whatsoever he shall say to you, do ye” (Jn 2:5). Now here is the word of Jesus Christ: “If you would enter into life, keep the commandments” (Mt 19:17). Let them each one fully convince himself of this, that if his piety towards the Blessed Virgin does not hinder him from sinning, or does not move his will to amend an evil life, it is a piety deceptive and Iying, wanting as it is in proper effect and its natural fruit.
If anyone desires a confirmation of this it may easily be found in the dogma of the Immaculate Conception of Mary. For leaving aside tradition which, as well as Scripture, is a source of truth, how has this persuasion of the Immaculate Conception of the Virgin appeared so conformed to the Catholic mind and feeling that it has been held as being one, and as it were inborn in the soul of the faithful? “We shrink from saying,” is the answer of Dionysius of Chartreux, “of this woman who was to crush the head of the serpent that had been crushed by him and that Mother of God that she had ever been a daughter of the Evil One”. No, to the Christian intelligence the idea is unthinkable that the flesh of Christ, holy, stainless, innocent, was formed in the womb of Mary of a flesh which had ever, if only for the briefest moment, contracted any stain. And why so, but because an infinite opposition separates God from sin? There certainly we have the origin of the conviction common to all Christians that Jesus Christ before, clothed in human nature, He cleansed us from our sins in His blood, accorded Mary the grace and special privilege of being preserved and exempted, from the first moment of her conception, from all stain of original sin.
If then God has such a horror of sin as to have willed to keep free the future Mother of His Son not only from stains which are voluntarily contracted but, by a special favour and in prevision of the merits of Jesus Christ, from that other stain of which the sad sign is transmitted to all us sons of Adam by a sort of hapless heritage: who can doubt that it is a duty for everyone who seeks by his homage to gain the heart of Mary to correct his vicious and depraved habits and to subdue the passions which incite him to evil?
Whoever moreover wishes, and no one ought not so to wish, that his devotion should be worthy of her and perfect, should go further and strive might and main to imitate her example. It is a divine law that those only attain everlasting happiness who have by such faithful following reproduced in themselves the form of the patience and sanctity of Jesus Christ: “for whom He foreknew, He also predestined to be made conformable to the image of His Son; that He might be the first-born amongst many brethren” (Rom 8: 29). But such generally is our infirmity that we are easily discouraged by the greatness of such an example: by the providence of God, however, another example is proposed to us, which is both as near to Christ as human nature allows, and more nearly accords with the weakness of our nature. And this is no other than the Mother of God. “Such was Mary,” very pertinently points out St Ambrose, “that her life is an example for all.” And, therefore, he rightly concludes: “Have then before your eyes, as an image, the virginity and life of Mary from whom as from a mirror shines forth the brightness of chastity and the form of virtue”.
What truly is the point of departure of the enemies of religion for the sowing of the great and serious errors by which the faith of so many is shaken? They begin by denying that man has fallen by sin and been cast down from his former position. Hence they regard as mere fables original sin and the evils that were its consequence. Humanity vitiated in its source vitiated in its turn the whole race of man; and thus was evil introduced amongst men and the necessity for a Redeemer involved. All this rejected it is easy to understand that no place is left for Christ, for the Church, for grace or for anything that is above and beyond nature; in one word the whole edifice of faith is shaken from top to bottom. But let people believe and confess that the Virgin Mary has been from the first moment of her conception preserved from all stain; and it is straightway necessary that they should admit both original sin and the rehabilitation of the human race by Jesus Christ, the Gospel, and the Church and the law of suffering.
We close these letters, Venerable Brethren, by manifesting anew the great hope We earnestly cherish that through this extraordinary gift of Jubilee granted by Us under the auspices of the Immaculate Virgin, large numbers of those who are unhappily separated from Jesus Christ may return to Him, and that love of virtue and fervour of devotion may flourish anew among the Christian people. True, we are passing through disastrous times, when we may well make our own the lamentation of the Prophet: “There is no truth and no mercy and no knowledge of God on the earth. Blasphemy and lying and homicide and theft and adultery have inundated it” (Os 4: 1–2). Yet in the midst of this deluge of evil, the Virgin Most Clement rises before our eyes like a rainbow, as the arbiter of peace between God and man: “I will set my bow in the clouds and it shall be the sign of a covenant between me and between the earth” (Gen 9:13). Let the storm rage and sky darken — not for that shall we be dismayed. “And the bow shall be in the clouds, and I shall see it and shall remember the everlasting covenant” (verse 16). “And there shall no more be waters of a flood to destroy all flesh” (verse 15). Oh yes, if we trust as we should in Mary, we shall recognise in her that Virgin most powerful “who with virginal foot did crush the head of the serpent”.
In pledge of these graces, Venerable Brethren, We impart the Apostolic Benediction lovingly in the Lord to you and to your people.
Given at Rome in St. Peter’s on the second day of February, 1904, in the first year of Our Pontificate.