The conception of a law common to the entire civilized world has received a new content and a practical interpretation through the recent development of international unions. The numerous private unions and associations for international purposes constitute a spontaneous grouping of men throughout the world who are interested in certain lines of enterprise — industrial, political, or scientific — which are not limited by national boundaries, but have the whole world for their field of action. The number of such associations already created is indeed surprising. Nearly every type of social effort for the promotion of the broader interests of mankind has been organized in this manner, so that there are literally hundreds of international unions and associations. These bodies hold periodical conferences for the interchange of opinions and the comparison of results, and in many cases they have established permanent bureaus or offices.