<P> One of the earliest references in Christian literature to the concept of the common good is found in the Epistle of Barnabas: "Do not live entirely isolated, having retreated into yourselves, as if you were already (fully) justified, but gather instead to seek together the common good ." </P> <P> The concept is strongly present in Augustine of Hippo's magnum opus City of God . Book XIX of this, the main locus of Augustine's normative political thought, is focused on the question,' Is the good life social?' In other words,' Is human wellbeing found in the good of the whole society, the common good?' Chapters 5 - 17 of Book XIX address this question . Augustine's emphatic answer is yes (see start of chap. 5). </P> <P> Augustine's understanding was taken up and, under the influence of Aristotle, developed by Thomas Aquinas . Aquinas's conception of the common good became standard in Roman Catholic moral theology . </P> <P> Against that background, the common good became a central concept in the modern tradition of Catholic social teaching, beginning with the foundational document, Rerum novarum, a papal encyclical by Pope Leo XIII, issued in 1891 . This addressed the crisis of the conditions of industrial workers in Europe and argued for a position different from both laissez - faire capitalism and socialism . In this letter, Pope Leo guarantees the right to private property while insisting on the role of collective bargaining to establish a living wage . </P>

Human dignity rights and the common good definition