51 In reality, besides commutative justice, there is also social justice with its own set obligations, from which neither employers nor workingmen can escape. Now it is of the very essence of social justice to demand from each individual all that is necessary for the common good. But just as in the living organism it is impossible to provide for the good of the whole unless each single part and each individual member is given what it needs for the exercise of its proper functions, so it is impossible to care for the social organism and the good of society as a unit unless each single part and each individual member - that is to say, each individual man in the dignity of his human personality - is supplied with all that is necessary for the exercise of his social functions. If social justice be satisfied, the result will be an intense activity in economic life as a whole, pursued in tranquillity and order. This activity will be proof of the health of the social body, just as the health of the human body is recognized in the undisturbed regularity and perfect efficiency of the whole organism.
Source: Divini Redemptoris (Vatican.va)