6 To Our great satisfaction, Venerable Brethren, you have, by means of individual and even joint pastoral Letters, accurately transmitted and explained to the Faithful these admonitions. Yet despite Our frequent and paternal warning the peril only grows greater from day to day because of the pressure exerted by clever agitators. Therefore We believe it to be Our duty to raise Our voice once more, in a still more solemn missive, in accord with the tradition of this Apostolic See, the Teacher of Truth, and in accord with the desire of the whole Catholic world, which makes the appearance of such a document but natural. We trust that the echo of Our voice will reach every mind free from prejudice and every heart sincerely desirous of the good of mankind. We wish this the more because Our words are now receiving sorry confirmation from the spectacle of the bitter fruits of subversive ideas, which We foresaw and foretold, and which are in fact multiplying fearfully in the countries already stricken, or threatening every other country of the world.
Source: Divini Redemptoris (Vatican.va)