49 The most important of all are workingmen's unions, for these virtually include all the rest. History attests what excellent results were brought about by the artificers' guilds of olden times. They were the means of affording not only many advantages to the workmen, but in no small degree of promoting the advancement of art, as numerous monuments remain to bear witness. Such unions should be suited to the requirements of this our age - an age of wider education, of different habits, and of far more numerous requirements in daily life. It is gratifying to know that there are actually in existence not a few associations of this nature, consisting either of workmen alone, or of workmen and employers together, but it were greatly to be desired that they should become more numerous and more efficient. We have spoken of them more than once, yet it will be well to explain here how notably they are needed, to show that they exist of their own right, and what should be their organization and their mode of action.
Source: Rerum Novarum (Vatican.va)