19 This concession places a duty on all Catholics to prepare themselves prudently and seriously for political life in case they may be called to it. Hence it is of the utmost importance that the same activity (previously so praiseworthily planned by Catholics for the purpose of preparing themselves by means of good electoral organization for the administrative life of common and provincial councils) be extended to a suitable preparation and organization for political life. This was already recommended by the Circular of December 3, 1904, issued by the general Presidency of Economic Works in Italy. At the same time the other principles which regulate the conscience of every true Catholic must be inculcated and put into practice. Above all else he must remember to be and to act in every circumstance as a true Catholic, accepting and fulfilling public offices with the firm and constant resolution of promoting by every means the social and economic welfare of the country and particularly of the people, according to the maxims of a truly Christian civilization, and at the same time defending the supreme interests of the Church, which are those of religion and justice.
Source: Il Fermo Proposito (Vatican.va)