Sacra Virginitas §56

⁵⁶ No doubt this pernicious method is based upon serious confusion of thought. Indeed Christ Our Lord asserted of His Apostles, "I have sent them into the world;" yet previously He had said of them, "They are not of the world, as I also am not of the world," and He had prayed to His Heavenly Father in these words, "I pray not that thou shouldst take them out of the world, but that thou shouldst keep them from evil." Motivated by the same principles, and in order to protect priests from temptations to evil, to which all those are ordinarily subject who are in intimate contact with the world, the Church has promulgated appropriate and wise laws, whose purpose is to safeguard sacerdotal sanctity from the cares and pleasures of the laity.