37 Faithful to these principles, the Church has given new life to human society. Under her influence arose prodigious charitable organizations, great guilds of artisans and workingmen of every type. These guilds, ridiculed as "medieval" by the liberalism of the last century, are today claiming the admiration of our contemporaries in many countries who are endeavoring to revive them in some modern form. And when other systems hindered her work and raised obstacles to the salutary influence of the Church, she was never done warning them of their error. We need but recall with what constant firmness and energy Our Predecessor, Leo XIII, vindicated for the workingman the right to organize, which the dominant liberalism of the more powerful States relentlessly denied him. Even today the authority of this Church doctrine is greater than it seems; for the influence of ideas in the realm of facts, though invisible and not easily measured, is surely of predominant importance.
Source: Divini Redemptoris (Vatican.va)