16 This Order, having for its object, as We have said to form its members in Christian perfection, even whilst they may be plunged in the embarrassments of the age, so true is it that no state of life is incompatible with sanctity, it happens, as it were, necessarily, where the Tertiaries in numbers observe faithfully their rule, that they are for all about them a source of encouragement in fulfilling their duties, and even to tending towards a perfection of life superior to the exigencies of the common law. The testimony rendered by the Divine Master to those who attached themselves closely to Him: "They are not of the world, even as I am not of the world" ( John xvii:16) may justly be applied to the sons of Francis who, if they observe the evangelical counsels of mind and heart as far as possible in the world, may lawfully put to their account the words of the Apostle: "As for us, we have received not the spirit of this world, but the Spirit which comes from God" (1 Cor ., 11:12).
Source: Sacra Propediem (Vatican.va)