137 But in effecting all this, the law of charity, "which is the bond of perfection," must always take a leading role. How completely deceived, therefore, are those rash reformers who concern themselves with the enforcement of justice alone - and this, commutative justice - and in their pride reject the assistance of charity! Admittedly, no vicarious charity can substitute for justice which is due as an obligation and is wrongfully denied. Yet even supposing that everyone should finally receive all that is due him, the widest field for charity will always remain open. For justice alone can, if faithfully observed, remove the causes of social conflict but can never bring about union of minds and hearts. Indeed all the institutions for the establishment of peace and the promotion of mutual help among men, however perfect these may seem, have the principal foundation of their stability in the mutual bond of minds and hearts whereby the members are united with one another. If this bond is lacking, the best of regulations come to naught, as we have learned by too frequent experience. And so, then only will true cooperation be possible for a single common good when the constituent parts of society deeply feel themselves members of one great family and children of the same Heavenly Father; nay, that they are one body in Christ, "but severally members one of another," so that "if one member suffers anything, all the members suffer with it." For then the rich and others in positions of power will change their former indifference toward their poorer brothers into a solicitous and active love, listen with kindliness to their just demands, and freely forgive their possible mistakes and faults. And the workers, sincerely putting aside every feeling of hatred or envy which the promoters of social conflict so cunningly exploit, will not only accept without rancor the place in human society assigned them by Divine Providence, but rather will hold it in esteem, knowing well that everyone according to his function and duty is toiling usefully and honorably for the common good and is following closely in the footsteps of Him Who, being in the form of God, willed to be a carpenter among men and be known as the son of a carpenter.
Source: Quadragesimo Anno (Vatican.va)