From Pope Benedict XVI’s encyclical Caritas in Veritate (2009):
One of the deepest forms of poverty a person can experience is isolation. If we look closely at other kinds of poverty, including material forms, we see that they are born from isolation, from not being loved or from difficulties in being able to love. Poverty is often produced by a rejection of God’s love, by man’s basic and tragic tendency to close in on himself, thinking himself to be self-sufficient or merely an insignificant and ephemeral fact, a “stranger” in a random universe. Man is alienated when he is alone, when he is detached from reality, when he stops thinking and believing in a foundation.125 All of humanity is alienated when too much trust is placed in merely human projects, ideologies and false utopias.126 Today humanity appears much more interactive than in the past: this shared sense of being close to one another must be transformed into true communion. The development of peoples depends, above all, on a recognition that the human race is a single family working together in true communion, not simply a group of subjects who happen to live side by side.127
Pope Paul VI noted that “the world is in trouble because of the lack of thinking.”128 He was making an observation, but also expressing a wish: a new trajectory of thinking is needed in order to arrive at a better understanding of the implications of our being one family; interaction among the peoples of the world calls us to embark upon this new trajectory, so that integration can signify solidarity129 rather than marginalization. Thinking of this kind requires a deeper critical evaluation of the category of relation. This is a task that cannot be undertaken by the social sciences alone, insofar as the contribution of disciplines such as metaphysics and theology is needed if man’s transcendent dignity is to be properly understood.
As a spiritual being, the human creature is defined through interpersonal relations. The more authentically he or she lives these relations, the more his or her own personal identity matures. It is not by isolation that man establishes his worth, but by placing himself in relation with others and with God. Hence these relations take on fundamental importance. The same holds true for peoples as well. A metaphysical understanding of the relations between persons is therefore of great benefit for their development. In this regard, reason finds inspiration and direction in Christian revelation, according to which the human community does not absorb the individual, annihilating his autonomy, as happens in the various forms of totalitarianism, but rather values him all the more because the relation between individual and community is a relation between one totality and another.130 Just as a family does not submerge the identities of its individual members, just as the Church rejoices in each “new creation” (Gal 6:15; 2 Cor 5:17) incorporated by Baptism into her living Body, so too the unity of the human family does not submerge the identities of individuals, peoples and cultures, but makes them more transparent to each other and links them more closely in their legitimate diversity.
The theme of development can be identified with the inclusion-in-relation of all individuals and peoples within the one community of the human family, built in solidarity on the basis of the fundamental values of justice and peace. This perspective is illuminated in a striking way by the relationship between the Persons of the Trinity within the one divine Substance. The Trinity is absolute unity insofar as the three divine Persons are pure relationality. The reciprocal transparency among the divine Persons is total and the bond between each of them complete, since they constitute a unique and absolute unity. God desires to incorporate us into this reality of communion as well: “that they may be one even as we are one” (Jn 17:22). The Church is a sign and instrument of this unity.131 Relationships between human beings throughout history cannot but be enriched by reference to this divine model. In particular, in the light of the revealed mystery of the Trinity, we understand that true openness does not mean loss of individual identity but profound interpenetration. This also emerges from the common human experiences of love and truth. Just as the sacramental love of spouses unites them spiritually in “one flesh” (Gen 2:24; Mt 19:5; Eph 5:31) and makes out of the two a real and relational unity, so in an analogous way truth unites spirits and causes them to think in unison, attracting them as a unity to itself.
125 Cf. John Paul II, Encyclical Letter Centesimus Annus, 41: Acta Apostolicæ Sedis [AAS] 83 (1991), 843-845.
126 Cf. ibid.
127 Cf. John Paul II, Encyclical Letter Evangelium Vitae, 20: AAS 87 (1995), 422-424.
128 Encyclical Letter Populorum Progressio, 85: AAS 59 (1967), 298-299.
129 Cf. John Paul II, Message for the 1998 World Day of Peace, 3: AAS 90 (1998), 150; Address to the Members of the Vatican Foundation “Centesimus Annus – Pro Pontifice”, 9 May 1998, 2; Address to the Civil Authorities and Diplomatic Corps of Austria, 20 June 1998, 8; Message to the Catholic University of the Sacred Heart, 5 May 2000, 6.
130 According to Saint Thomas “ratio partis contrariatur rationi personæ”, In III Sent., d. 5, q. 3, a. 2; also “Homo non ordinatur ad communitatem politicam secundum se totum et secundum omnia sua”, Summa Theologiæ I-II, q. 21, a. 4, ad 3.
131 Cf. Second Vatican Ecumenical Council, Dogmatic Constitution on the Church Lumen Gentium, 1.
— Caritas in Veritate 53-54