To Our Venerable Brothers, all Patriarchs, Primates, Metropolitans, Archbishops, and Bishops Who Enjoy Grace and Communion with the Apostolic See.

Venerable Brothers, Greetings and Apostolic Blessing.

The well-being of the Christian community which has been entrusted to Us by the Prince of shepherds and the Guardian of souls requires Us to see to it that the unaccustomed and offensive licentiousness of books which has emerged from hiding to cause ruin and desolation does not become more destructive as it triumphantly spreads abroad. The distortion of this hateful error and the boldness of the enemy has so increased, especially at this time, in sowing weeds among the wheat either in word or in writing that unless We lay the scythe to the root and bind up the bad plants in bundles to burn, it will not be long before the growing thorns of evil attempt to choke the seedlings of the Lord Sabaoth. For accursed men who have given themselves over to myths and who do not uphold the stronghold of Sion from all sides vomit the poison of serpents from their hearts for the ruin of the Christian people by the contagious plague of books which almost overwhelms us. They pollute the pure waters of belief and destroy the foundations of religion.

They are abominable in their activity. Secretly sitting in ambush, they draw arrows out of the quiver which they shoot at the righteous in the dark. They have not restrained their impious minds from anything divine, holy, and consecrated by the oldest religion of all time; rather in their attack they have sharpened their tongues like a sword. They have run first of all against God in their pride. Armed with a thick neck, they have strengthened themselves against the Almighty. They raise again from the ashes the absurdities of the impious which have been destroyed so often. They deny God even though He makes Himself known everywhere and comes before their eyes daily, not because of the dullness of their mind, but only on the urging of their depraved will. Or else they represent God Himself as lazy and indolent. They do not respect His providence nor do they fear His justice. They preach with a detestable and insane freedom of thought that the origin and nature of our soul is mortal although it was created in the image of the supreme creator little lower than the angels. Whether they think matter has been created or foolishly imagine that it is eternal and independent of the causes, they consider that nothing else exists in this universe. Or else if they are forced to admit that spirit exists with matter, they exclude the soul from the spirit's heavenly nature. They are unwilling to understand that in this very weakness of which we are formed something spiritual and incorruptible abides in us. By its power we know, act, will, look to the future, attend to the present, and remember the past.

On the other hand, there are others who, even if they judge correctly that the fog of earthly reasonings should be dispelled and the smoke of worldly wisdom should be driven from the eye of enlightened faith, still dare to examine with human measures the hidden mysteries of faith which surpass all understanding. Having become investigators of greatness, they are not afraid of being overwhelmed by its glory. They ridicule the faith of simple people. They lay open the mysteries of God. They rashly discourse on questions concerning the highest matters. The bold mind of the enquirer takes everything for itself, examines everything, reserves nothing for faith, and deprives faith of merit by seeking proof for it in human reason.

Should we not also be angry with those who use the most wicked indecency of word and example to corrupt pure and strict morals by mortal sin, who recommend to the minds of the unwary an accursed license of living, and who cause an extreme loss of faith? Then consider how they sprinkle their writings with a certain refined splendor, a seductive pleasantness of speech and allurement so as to penetrate more easily into the readers' minds and infect them more deeply with the poison of their error. Thus they will give the snake's poison in the cup of Babylon to the unwary who are seduced and blinded by their smooth speech and so do not recognize the poison that kills them. Finally, who can avoid deep sadness when he sees the bitter enemy exceed the bounds of modesty and due respect and attack with the publication of outrageous books now in open battle, now in dissimulated combat the very See of Peter which the strong redeemer of Jacob has placed as an iron column and as a bronze wall against the leaders of darkness. Perhaps they are led on by the desperate thought that if they shatter the head of the Church, they will be able more freely to tear to pieces its members.

2. Therefore since the Holy Spirit has made you bishops to govern the Church of God and has taught you concerning the unique sacrament of human salvation, We cannot neglect our duty in the face of these evil books. We must arouse the enthusiasm of your devotion so that you, who are called to share in Our pastoral concern join together to oppose this evil with all energy possible. It is necessary to fight bitterly, as the situation requires, and to eradicate with all our strength the deadly destruction caused by such books. The substance of the error will never be removed unless the criminal elements of wickedness burn in the fire and perish. Since you have been constituted stewards of the mysteries of God and armed with His strength to destroy their defenses, exert yourselves to keep the sheep entrusted to you and redeemed by the blood of Christ at a safe distance from these poisoned pastures. For if it is necessary to avoid the company of evildoers because their words encourage impiety and their speech acts like a cancer, what desolation the plague of their books can cause! Well and cunningly written these books are always with us and forever within our reach. They travel with us, stay at home with us, and enter bedrooms which would be shut to their evil and deception.

Since you have been constituted ministers of Christ for the nations, in order to make holy his Gospel, exert yourselves and do everything in your power both by word and example to cut down the shoots of falsehood. Block up the corrupt springs of vice. Sound the trumpet in case as their leader you have to account for the souls who are lost. Act according to the position you hold, according to the rank with which you are vested, and according to the authority which you have received from the Lord. In addition, as nobody could or should avoid sharing in this sadness and insofar as there is one common reason for everyone to grieve and to help in this great crisis of faith and religion, call to your aid when it is necessary the time-honored piety of Catholic leaders. Explain the cause of the Church's sorrow and arouse its beloved sons who have always served it well on many occasions to bring their help. Since they do not carry the sword without cause, urge them with the united authority of state and of priesthood, to vigorously rout those accursed men who fight against the armies of Israel.

It is principally your duty to stand as a wall so that no foundation can be laid other than the one that is already laid. Watch over the most holy deposit of faith to whose protection you committed yourselves on oath at your solemn consecration. Reveal to the faithful the wolves which are demolishing the Lord's vineyard. They should be warned not to allow themselves to be ensnared by the splendid writing of certain authors in order to halt the diffusion of error by cunning and wicked men. In a word, they should detest books which contain elements shocking to the reader; which are contrary to faith, religion, and good morals; and which lack an atmosphere of Christian virtue. We manifest to you Our great happiness in this matter that most of you, following the apostolic customs and energetically defending the laws of the Church, have shown yourselves zealous and watchful in order to avert this pestilence and have not allowed the simple people to sleep soundly with serpents.

Certainly We who are distressed and distracted by Our concern for all the churches and for the salvation of the Christian people, are unsparing of Our efforts, and We promise you assistance too in your own grave danger. Meanwhile, We will not cease to ask God with deep humility to grant you help from His holy place to deflect the cunning of the insidious enemy and to entirely fulfill the duties of your ministry. As a pledge of the desired outcome, we lovingly impart Our apostolic blessing to you and your flock.

Given in Rome in St. Mary Major's on the 25th day of November in the year 1766, the ninth year of Our pontificate.