12 In the first place comes the family, instituted directly by God for its peculiar purpose, the generation and formation of offspring; for this reason it has priority of nature and therefore of rights over civil society. Nevertheless, the family is an imperfect society, since it has not in itself all the means for its own complete development; whereas civil society is a perfect society, having in itself all the means for its peculiar end, which is the temporal well-being of the community; and so, in this respect, that is, in view of the common good, it has pre-eminence over the family, which finds its own suitable temporal perfection precisely in civil society.
Source: Divini Illius Magistri (Vatican.va)