Catholics have just reasons for taking part in the conduct of public affairs. For in so doing they assume not nor should they assume the responsibility of approving what is blameworthy in the actual methods of government, but seek to turn these very methods, so far as is possible, to the genuine and true public good, and to use their best endeavours at the same time to infuse, as it were, into all the veins of the State the healthy sap and blood of Christian wisdom and virtue. The morals and ambitions of the heathens differed widely from those of the Gospel, yet Christians were to be seen living undefiled everywhere in the midst of pagan superstition, and, while always true to themselves, coming to the front boldly wherever an opening was presented. Models of loyalty to their rulers, submissive, so far as was permitted, to the sovereign power, they shed around them on every side a halo of sanctity; they strove to be helpful to their brethren, and to attract others to the wisdom of Jesus Christ, yet were bravely ready to withdraw from public life, nay, even to lay down their life, if they could not without loss of virtue retain honours, dignities, and offices.
–Leo XIII, Immortale Dei 45