Pope John XXIII - 1960
To his Venerable Brother Patriarchs, Primates, Archbishops, Bishops and other Local Ordinaries in Peace and Communion with the Apostolic See
Venerable brethren: greetings and apostolic blessings.
From the very outset of our pontificate, in speaking of daily devotions we have repeatedly urged the faithful (often in eager tones that frankly hinted our future design) to cherish warmly that marvellous manifestation of divine mercy toward individuals and Holy Church and the whole world redeemed and saved by Jesus Christ: we mean devotion to his Most Precious Blood.
From infancy this devotion was instilled in us within our own household. Fondly we still recall how our parents used to recite the Litany of the Most Precious Blood every day during July.
The Apostle’s wholesome advice comes to mind: “Keep watch, then, over yourselves, and over God’s Church, in which the Holy Spirit has made you bishops; you are to be the shepherds of that flock which he won for himself at the price of his own blood.” Now among the cares of our pastoral office, venerable brethren, we are convinced that, second only to vigilance over sound doctrine, preference belongs to the proper surveillance and development of piety, in both its liturgical and private expressions. With that in mind, we judge it most timely to call our beloved children’s attention to the unbreakable bond which must exist between the devotions to the Most Holy Name and Most Sacred Heart of Jesus — already so widespread among Christianns — and devotion to the incarnate Word’s Most Precious Blood, “shed for many, to the remission of sins.”
It is supremely important that the Church’s liturgy fully conform to Catholic belief (“the law for prayer is the law for faith”), and that only those devotional forms be sanctioned which well up from the unsullied springs of true faith. But the same logic calls for complete accord among different devotions. Those deemed more basic and more conducive to holiness must not be at odds with or cut off from one another. And the more individualistic and secondary ones must give way in popularity and practice to those devotions which more effectively actuate the fullness of salvation wrought by the “one mediator between God and men, Jesus Christ, who is a man, like them, and gave himself as a ransom for them all.”  Through living in an atmosphere thus charged with true faith and solid piety the faithful can be confident that they are “thinking with the Church” and holding fast in the loving fellowship of prayer to Christ Jesus, the high priest of that sublime religion which he founded and which owes to him its name, its strength, its dignity.
The Church’s wonderful advances in liturgical piety match the progress of faith itself in penetrating divine truth. Within this development it is most heart-warming to observe how often in recent centuries this Holy See has openly ap proved and furthered the three devotions just mentioned. From the Middle Ages, it is true, many pious persons prac ticed these devotions, which then spread to various dioceses and religious orders and congregations. Nevertheless it remained for the Chair of Peter to pronounce them orthodox and approve them for the Church as a whole.
Suffice it to recall the spiritual favours that our predecessors from the sixteenth century on have attached to prac ticing devotion to the Most Holy Name of Jesus, which in the previous century St. Bernardine of Siena untiringly spread throughout Italy. Approval was given first to the Office and Mass of the Most Holy Name and later to the Litany. No less striking are the benefits the popes have attached to practising devotion to the Most Sacred Heart of Jesus, whose rise and spread owe so much to the revelations of the Sacred Heart to St. Margaret Mary Alacoque. So highly have all the popes regarded this devotion that again and again in their official acts they have expounded its nature, defended its validity, promoted its practice. Their crowning achievement on this devotion are three splendid encyclicals.