I answer that, As stated above (A. 2), difference among the members of the Church is directed to three things: perfection, action, and beauty; and according to these three we may distinguish a threefold distinction among the faithful. One, with regard to perfection, and thus we have the difference of states, in reference to which some persons are more perfect than others. Another distinction regards action and this is the distinction of duties: for persons are said to have various duties when they are appointed to various actions. A third distinction regards the order of ecclesiastical beauty: and thus we distinguish various grades according as in the same state or duty one person is above another. Hence according to a variant text [*The Septuagint] it is written (Ps. 47:4): "In her grades shall God be known."
Reply Obj. 1: The material diversity of human acts is infinite. It is not thus that duties differ, but by their formal diversity which results from diverse species of acts, and in this way human acts are not infinite.
Reply Obj. 2: Life is predicated of a thing absolutely: wherefore diversity of lives results from a diversity of acts which are becoming to man considered in himself. But efficiency, whence we have the word "office" (as stated above), denotes action tending to something else according to Metaph. ix, text. 16 [*Ed. Did. viii, 8]. Hence offices differ properly in respect of acts that are referred to other persons; thus a teacher is said to have an office, and so is a judge, and so forth. Wherefore Isidore says (Etym. vi, 19) that "to have an office is to be officious," i.e. harmful "to no one, but to be useful to all."
Reply Obj. 3: Differences of state, offices and grades are taken from different things, as stated above (A. 1, ad 3). Yet these three things may concur in the same subject: thus when a person is appointed to a higher action, he attains thereby both office and grade, and sometimes, besides this, a state of perfection, on account of the sublimity of the act, as in the case of a bishop. The ecclesiastical orders are particularly distinct according to divine offices. For Isidore says (Etym. vi): "There are various kinds of offices; but the foremost is that which relates to sacred and Divine things." _______________________
FOURTH ARTICLE [II-II, Q. 183, Art. 4]
Whether the Difference of States Applies to Those Who Are Beginning,
Progressing, or Perfect?
Objection 1: It would seem that the difference of states does not apply to those who are beginning, progressing, or perfect. For "diverse genera have diverse species and differences" [*Aristotle, Categ. ii]. Now this difference of beginning, progress, and perfection is applied to the degrees of charity, as stated above (Q. 24, A. 9), where we were treating of charity. Therefore it would seem that the differences of states should not be assigned in this manner.
Obj. 2: Further, as stated above (A. 1), state regards a condition of servitude or freedom, which apparently has no connection with the aforesaid difference of beginning, progress, and perfection. Therefore it is unfitting to divide state in this way.
Obj. 3: Further, the distinction of beginning, progress, and perfection seems to refer to more and less, and this seemingly implies the notion of grades. But the distinction of grades differs from that of states, as we have said above (AA. 2, 3). Therefore state is unfittingly divided according to beginning, progress, and perfection.
On the contrary, Gregory says (Moral. xxiv, 11): "There are three states of the converted, the beginning, the middle, and the perfection"; and (Hom. xv in Ezech.): "Other is the beginning of virtue, other its progress, and other still its perfection."