3.--Change and diversity also mark the relationships between the wage earners and the other industrial groups. Up to the very recent past, the connection of the wage earners with the enterprise in which they served was limited practically to the fulfillment of the individual wage contracts which were made. The obligation of the wage earners to the enterprise which employed them has been considered at an end with the performance of the work they were employed to do. Similarly, the obligation of the enterprise to the wage earners has been considered fulfilled by the payment of wages earned. The wage earners have been called upon to give their whole-hearted efforts to their work by reason of the belief that such effort was to their own interest, and by reason of their own hopes and desires for advancement. The American wage earners have usually tackled their jobs with energy, good will, and sincerity. It is impossible to attempt to sketch here the development of the practice of collective bargaining, and the various concepts of industrial relationship to which the rise of trade unionism has given impulse. We are now in the midst of a struggle brought about by the efforts of the wage earners to add to their traditional rights of freedom of contract and of enterprise certain other rights. These may be collectively described as the right to organize and to use their organized strength collectively in all ways which may be reconciled with the public interest. Some of the greatest industrial conflicts of recent years have been consequences of the efforts of the wage earners to establish these additional rights both in fact and in law (as for example the strike in the steel and iron industry in 1919). Much headway has been made in the establishment of the rule of collective bargaining in industry. The scope of the matters usually settled by that method varies greatly between individual, establishments and industries.