l and Labor That the spirit of revolutionary change, which has long been disturbing the nations of the world, should have passed beyond the sphere of politics and made its influence felt in the cognate sphere of practical economics is not surprising. The elements of the conflict now raging are unmistakable, in the vast expansion of industrial pursuits and the marvelous discoveries of science; in the changed relations between masters and workmen; in the enormous fortunes of some few individuals, and the utter poverty of the masses; the increased self-reliance and closer mutual combination of the working classes; as also, finally, in the prevailing moral degeneracy. The momentous gravity of the state of things now obtaining fills every mind with painful apprehension; wise men are discussing it; practical men are proposing schemes; popular meetings, legislatures, and rulers of nations are all busied with it - actually there is no question which has taken deeper hold on the public mind. 2. Therefore, venerable brethren, as on former occasions when it seemed opportune to refute false teaching, We have addressed you in the interests of the Church and of the common weal, and have issued letters bearing on political power, human liberty, the Christian constitution of the State, and like matters, so have We thought it expedient now to speak on the condition of the working classes. It is a subject on which We have already touched more than once, incidentally. But in the present letter, the responsibility of the apostolic office urges Us to treat the question of set purpose and in detail, in order that no misapprehension may exist as to the principles which truth and justice dictate for its settlement. The discussion is not easy, nor is it void of danger. It is no easy matter to define the relative rights and mutual duties of the rich and of the poor, of capital and of labor. And the danger lies in this, that crafty agitators are intent on making use of these differences of opinion to pervert men's judgments and to stir up the people to revolt.