204. Among the virtues in their entirety, and in particular between virtues, social values and love, there exists a deep bond that must be ever more fully recognized. Love, often restricted to relationships of physical closeness or limited to merely subjective aspects of action on behalf of others, must be reconsidered in its authentic value as the highest and universal criterion of the whole of social ethics. Among all paths, even those sought and taken in order to respond to the ever new forms of current social questions, the “more excellent way” (cf. 1 Cor 12:31) is that marked out by love.
205. It is from the inner wellspring of love that the values of truth, freedom and justice are born and grow. Human life in society is ordered, bears fruits of goodness and responds to human dignity when it is founded on truth; when it is lived in justice, that is, in the effective respect of rights and in the faithful carrying out of corresponding duties; when it is animated by selflessness, which makes the needs and requirements of others seem as one's own and intensifies the communion of spiritual values and the concern for material necessities; when it is brought about in the freedom that befits the dignity of men and women, prompted by their rational nature to accept responsibility for their actions[451]. These values constitute the pillars which give strength and consistency to the edifice of life and deeds: they are values that determine the quality of every social action and institution.
206. Love presupposes and transcends justice, which “must find its fulfilment in charity”[452]. If justice is “in itself suitable for ‘arbitration' between people concerning the reciprocal distribution of objective goods in an equitable manner, love and only love (including that kindly love that we call ‘mercy') is capable of restoring man to himself”[453]. Human relationships cannot be governed solely by the measure of justice: “The experience of the past and of our own time demonstrates that justice alone is not enough, that it can even lead to the negation and destruction of itself ... It has been precisely historical experience that, among other things, has led to the formulation of the saying: summum ius, summa iniuria”[454]. In fact, “in every sphere of interpersonal relationships justice must, so to speak, be ‘corrected' to a considerable extent by that love which, as St. Paul proclaims, ‘is patient and kind' or, in other words, possesses the characteristics of that merciful love which is so much of the essence of the Gospel and Christianity”[455].
207. No legislation, no system of rules or negotiation will ever succeed in persuading men and peoples to live in unity, brotherhood and peace; no line of reasoning will ever be able to surpass the appeal of love. Only love, in its quality as “form of the virtues”[456], can animate and shape social interaction, moving it towards peace in the context of a world that is ever more complex. In order that all this may take place, however, it is necessary that care be taken to show love not only in its role of prompting individual deeds but also as a force capable of inspiring new ways of approaching the problems of today's world, of profoundly renewing structures, social organizations, legal systems from within. In this perspective love takes on the characteristic style of social and political charity: “Social charity makes us love the common good”[457], it makes us effectively seek the good of all people, considered not only as individuals or private persons but also in the social dimension that unites them.
208. Social and political charity is not exhausted in relationships between individuals but spreads into the network formed by these relationships, which is precisely the social and political community; it intervenes in this context seeking the greatest good for the community in its entirety. In so many aspects the neighbour to be loved is found “in society”, such that to love him concretely, assist him in his needs or in his indigence may mean something different than it means on the mere level of relationships between individuals. To love him on the social level means, depending on the situations, to make use of social mediations to improve his life or to remove social factors that cause his indigence. It is undoubtedly an act of love, the work of mercy by which one responds here and now to a real and impelling need of one's neighbour, but it is an equally indispensable act of love to strive to organize and structure society so that one's neighbour will not find himself in poverty, above all when this becomes a situation within which an immense number of people and entire populations must struggle, and when it takes on the proportions of a true worldwide social issue.

thanks to vatican.va