I answer that, As stated above (Q. 141, A. 2) that which is applicable to many things in common is ascribed antonomastically to that to which it is applicable by way of excellence. Thus the name of "fortitude" is claimed by the virtue which preserves the firmness of the mind in regard to most difficult things, and the name of "temperance," by that virtue which tempers the greatest pleasures. Now religion as stated above (Q. 81, A. 2; A. 3, ad 2) is a virtue whereby a man offers something to the service and worship of God. Wherefore those are called religious antonomastically, who give themselves up entirely to the divine service, as offering a holocaust to God. Hence Gregory says (Hom. xx in Ezech.): "Some there are who keep nothing for themselves, but sacrifice to almighty God their tongue, their senses, their life, and the property they possess." Now the perfection of man consists in adhering wholly to God, as stated above (Q. 184, A. 2), and in this sense religion denotes the state of perfection.
Reply Obj. 1: To offer something to the worship of God is necessary for salvation, but to offer oneself wholly, and one's possessions to the worship of God belongs to perfection.
Reply Obj. 2: As stated above (Q. 81, A. 1, ad 1; A. 4, ad 1, 2; Q. 85, A. 3) when we were treating of the virtue of religion, religion has reference not only to the offering of sacrifices and other like things that are proper to religion, but also to the acts of all the virtues which in so far as these are referred to God's service and honor become acts of religion. Accordingly if a man devotes his whole life to the divine service, his whole life belongs to religion, and thus by reason of the religious life that they lead, those who are in the state of perfection are called religious.
Reply Obj. 3: As stated above (Q. 184, AA. 4, 6) religion denotes the state of perfection by reason of the end intended. Hence it does not follow that whoever is in the state of perfection is already perfect, but that he tends to perfection. Hence Origen commenting on Matt. 19:21, "If thou wilt be perfect," etc., says (Tract. viii in Matth.) that "he who has exchanged riches for poverty in order to become perfect does not become perfect at the very moment of giving his goods to the poor; but from that day the contemplation of God will begin to lead him to all the virtues." Thus all are not perfect in religion, but some are beginners, some proficient.
Reply Obj. 4: The religious state was instituted chiefly that we might obtain perfection by means of certain exercises, whereby the obstacles to perfect charity are removed. By the removal of the obstacles of perfect charity, much more are the occasions of sin cut off, for sin destroys charity altogether. Wherefore since it belongs to penance to cut out the causes of sin, it follows that the religious state is a most fitting place for penance. Hence (XXXIII, qu. ii, cap. Admonere) a man who had killed his wife is counseled to enter a monastery which is described as "better and lighter," rather than to do public penance while remaining in the world. _______________________
SECOND ARTICLE [II-II, Q. 186, Art. 2]
Whether Every Religious Is Bound to Keep All the Counsels?
Objection 1: It would seem that every religious is bound to keep all the counsels. For whoever professes a certain state of life is bound to observe whatever belongs to that state. Now each religious professes the state of perfection. Therefore every religious is bound to keep all the counsels that pertain to the state of perfection.
Obj. 2: Further, Gregory says (Hom. xx in Ezech.) that "he who renounces this world, and does all the good he can, is like one who has gone out of Egypt and offers sacrifice in the wilderness." Now it belongs specially to religious to renounce the world. Therefore it belongs to them also to do all the good they can. and so it would seem that each of them is bound to fulfil all the counsels.
Obj. 3: Further, if it is not requisite for the state of perfection to fulfil all the counsels, it would seem enough to fulfil some of them. But this is false, since some who lead a secular life fulfil some of the counsels, for instance those who observe continence. Therefore it would seem that every religious who is in the state of perfection is bound to fulfil whatever pertains to perfection: and such are the counsels.