Longinqua §15

¹⁵ As regards civil affairs, experience has shown how important it is that the citizens should be upright and virtuous. In a free State, unless justice be generally cultivated, unless the people be repeatedly and diligently urged to observe the precepts and laws of the Gospel, liberty itself may be pernicious. Let those of the clergy, therefore, who are occupied with the instruction of the multitude, treat plainly this topic of the duties of citizens, so that all may understand and feel the necessity, in political life, of conscientiousness, self restraint, and integrity; for that cannot be lawful in public which is unlawful in private affairs. On this whole subject there are to be found, as you know, in the encyclical letters written by Us from time to time in the course of Our pontificate, many things which Catholics should attend to and observe. In these writings and expositions We have treated of human liberty, of the chief Christian duties, of civil government, and of the Christian constitution of States, drawing Our principles as well from the teaching of the Gospels as from reason. They, then, who wish to be good citizens and discharge their duties faithfully may readily learn from Our Letters the ideal of an upright life. In like manner, let the priests be persistent in keeping before the minds of the people the enactments of the Third Council of Baltimore, particularly those which inculcate the virtue of temperance, the frequent use of the sacraments and the observance of the just laws and institutions of the Republic.