Libertas §34

³⁴ But, to judge aright, we must acknowledge that, the more a State is driven to tolerate evil, the further is it from perfection; and that the tolerance of evil which is dictated by political prudence should be strictly confined to the limits which its justifying cause, the public welfare, requires. Wherefore, if such tolerance would be injurious to the public welfare, and entail greater evils on the State, it would not be lawful; for in such case the motive of good is wanting. And although in the extraordinary condition of these times the Church usually acquiesces in certain modern liberties, not because she prefers them in themselves, but because she judges it expedient to permit them, she would in happier times exercise her own liberty; and, by persuasion, exhortation, and entreaty would endeavor, as she is bound, to fulfill the duty assigned to her by God of providing for the eternal salvation of mankind. One thing, however, remains always true - that the liberty which is claimed for all to do all things is not, as We have often said, of itself desirable, inasmuch as it is contrary to reason that error and truth should have equal rights.