59 Hence, it is the noble prerogative and function of the State to control, aid and direct the private and individual activities of national life that they converge harmoniously towards the common good. That good can neither be defined according to arbitrary ideas nor can it accept for its standard primarily the material prosperity of society, but rather it should be defined according to the harmonious development and the natural perfection of man. It is for this perfection that society is designed by the Creator as a means.
Source: Summi Pontificatus (Vatican.va)