The following November, he addressed this encyclical to "All Patriarchs, Primates, Archbishops, and Bishops", exhorting them to be vigilant against the dangers of rationalism, pantheism, Communism, and modernity.

Its purpose is to urge that you keep the night-watches over the flock entrusted to your care with the greatest possible eagerness, wakefulness and effort..."[1] According to Thomas W. O'Brien, much of the document was drafted by Luigi Cardinal Lambruschini, Secretary of State to Pius's predecessor, the strongly conservative Pope Gregory XVI.

[2] The encyclical is particularly directed against socialists and communists, who through "their outlandish errors and their many harmful methods, plots and contrivances... which they use to set in motion their plans to quench peoples’ zeal for piety, justice and virtue, to corrupt morals, to cast all divine and human laws into confusion, and to weaken and even possibly overthrow the Catholic religion and civil society.

[8][9] In 1844, Pope Gregory XVI issued the Encyclical, "Inter praecipuas machinationes", against the anti-Catholic propaganda in Italy of the London Bible Society and the New York Christian Alliance, which endeavoured with some success, in spreading anti-clericalism among the populace.

The commentaries which are included often contain perverse explanations; so, having rejected divine tradition, the doctrine of the Fathers and the authority of the Catholic Church, they all interpret the words of the Lord by their own private judgment, thereby perverting their meaning.

"You must examine with greater diligence the morals and the knowledge of men who are entrusted with the care and guidance of souls, that they may be eager to continuously feed and assist the people entrusted to them by the administration of the sacraments, the preaching of God’s word and the example of good works...Consecrate with holy orders and promote to the performance of the sacred mysteries only those who have been carefully examined and who are virtuous and wise.