The Church’s understanding of the human person as well as her understanding of the family and marriage are beautiful, and timely (timeless!).
Today’s instruction comes from the Compendium Of The Social Doctrine Of The Church. I apologize that the footnotes are not included, but for further reading and study, you may access the entire document through the Vatican Website:
213. The family, the natural community in which human social nature is experienced, makes a unique and irreplaceable contribution to the good of society. The family unit, in fact, is born from the communion of persons. “‘Communion‘ has to do with the personal relationship between the ‘I’ and the ‘thou’. ‘Community‘ on the other hand transcends this framework and moves towards a ‘society’, a ‘we’. The family, as a community of persons, is thus the first human ‘society’“.
A society built on a family scale is the best guarantee against drifting off course into individualism or collectivism, because within the family the person is always at the centre of attention as an end and never as a means. It is patently clear that the good of persons and the proper functioning of society are closely connected “with the healthy state of conjugal and family life”. Without families that are strong in their communion and stable in their commitment peoples grow weak. In the family, moral values are taught starting from the very first years of life, the spiritual heritage of the religious community and the cultural legacy of the nation are transmitted. In the family one learns social responsibility and solidarity.
214. The priority of the family over society and over the State must be affirmed. The family in fact, at least in its procreative function, is the condition itself for their existence. With regard to other functions that benefit each of its members, it proceeds in importance and value the functions that society and the State are called to perform. The family possesses inviolable rights and finds its legitimization in human nature and not in being recognized by the State. The family, then, does not exist for society or the State, but society and the State exist for the family.
Every social model that intends to serve the good of man must not overlook the centrality and social responsibility of the family. In their relationship to the family, society and the State are seriously obligated to observe the principle of subsidiarity. In virtue of this principle, public authorities may not take away from the family tasks which it can accomplish well by itself or in free association with other families; on the other hand, these same authorities have the duty to sustain the family, ensuring that it has all the assistance that it needs to fulfil properly its responsibilities.
II. MARRIAGE, THE FOUNDATION OF THE FAMILY
215. The family has its foundation in the free choice of the spouses to unite themselves in marriage, in respect for the meaning and values of this institution that does not depend on man but on God himself: “For the good of the spouses and their offspring as well as of society, this sacred bond no longer depends on human decision alone. For God himself is the author of marriage and has endowed it with various benefits and purposes”. Therefore, the institution of marriage — “intimate partnership of life and love … established by the Creator and endowed by him with its own proper laws”  — is not the result of human conventions or of legislative prescriptions but acquires its stability from divine disposition. It is an institution born, even in the eyes of society, “from the human act by which the partners mutually surrender themselves to each other”, and is founded on the very nature of that conjugal love which, as a total and exclusive gift of person to person, entails a definitive commitment expressed by mutual, irrevocable and public consent. This commitment means that the relationships among family members are marked also by a sense of justice and, therefore, by respect for mutual rights and duties.
216. No power can abolish the natural right to marriage or modify its traits and purpose. Marriage in fact is endowed with its own proper, innate and permanent characteristics.