Objection 1. It would seem that the aureole is not distinct from the essential reward which is called the "aurea." For the essential reward is beatitude itself. Now according to Boethius (De Consol. iii), beatitude is "a state rendered perfect by the aggregate of all goods." Therefore the essential reward includes every good possessed in heaven; so that the aureole is included in the "aurea."
Objection 2. Further, "more" and "less" do not change a species. But those who keep the counsels and commandments receive a greater reward than those who keep the commandments only, nor seemingly does their reward differ, except in one reward being greater than another. Since then the aureole denotes the reward due to works of perfection it would seem that it does not signify something distinct from the "aurea."
Objection 3. Further, reward corresponds to merit. Now charity is the root of all merit. Since then the "aurea" corresponds to charity, it would seem that there will be no reward in heaven other than the "aurea."
Objection 4. Further, "All the blessed are taken into the angelic orders" as Gregory declares (Hom. xxxiv in Evang.). Now as regards the angels, "though some of them receive certain gifts in a higher degree, nothing is possessed by any of them exclusively, for all gifts are in all of them, though not equally, because some are endowed more highly than others with gifts which, however, they all possess," as Gregory says (Hom. xxxiv in Evang.). Therefore as regards the blessed, there will be no reward other than that which is common to all. Therefore the aureole is not a distinct reward from the "aurea."
Objection 5. Further, a higher reward is due to higher merit. If, then, the "aurea" is due to works which are of obligation, and the aureole to works of counsel, the aureole will be more perfect than the "aurea," and consequently should not be expressed by a diminutive ["Aureola," i.e. a little "aurea"]. Therefore it would seem that the aureole is not a distinct reward from the "aurea."
On the contrary, A gloss [Ven. Bede, De Tabernaculis i, 6 on Exodus 25:24-25, "Thou shalt make... another little golden crown [coronam aureolam]," says: "This crown denotes the new hymn which the virgins alone sing in the presence of the Lamb." Wherefore apparently the aureole is a crown awarded, not to all, but especially to some: whereas the aurea is awarded to all the blessed. Therefore the aureole is distinct from the "aurea."
Further, a crown is due to the fight which is followed by victory: "He... is not crowned except he strive lawfully" (2 Timothy 2:5). Hence where there is a special kind of conflict, there should be a special crown. Now in certain works there is a special kind of conflict. Therefore they deserve a special kind of crown, which we call an aureole.
Further, the Church militant comes down from the Church triumphant: "I saw the Holy City," etc. (Apocalypse 21:2). Now in the Church militant special rewards are given to those who perform special deeds, for instance a crown to the conqueror, a prize to the runner. Therefore the same should obtain in the Church triumphant.
I answer that, Man's essential reward, which is his beatitude, consists in the perfect union of the soul with God, inasmuch as it enjoys God perfectly as seen and loved perfectly. Now this reward is called a "crown" or "aurea" metaphorically, both with reference to merit which is gained by a kind of conflict--since "the life of man upon earth is a warfare" (Job 7:1)--and with reference to the reward whereby in a way man is made a participator of the Godhead, and consequently endowed with regal power: "Thou hast made us to our God a kingdom," etc. (Apocalypse 5:10); for a crown is the proper sign of regal power.
In like manner the accidental reward which is added to the essential has the character of a crown. For a crown signifies some kind of perfection, on account of its circular shape, so that for this very reason it is becoming to the perfection of the blessed. Since, however, nothing can be added to the essential, but what is less than it, the additional reward is called an "aureole." Now something may be added in two ways to this essential reward which we call the "aurea." First, in consequence of a condition attaching to the nature of the one rewarded: thus the glory of the body is added to the beatitude of the soul, wherefore this same glory of the body is sometimes called an "aureole." Thus a gloss of Bede on Exodus 25:25, "Thou... shalt make another little golden crown," says that "finally the aureole is added, when it is stated in the Scriptures that a higher degree of glory is in store for us when our bodies are resumed." But it is not in this sense that we speak of an aureole now. Secondly, in consequence of the nature of the meritorious act. Now this has the character of merit on two counts, whence also it has the character of good. First, to wit, from its root which is charity, since it is referred to the last end, and thus there is due to it the essential reward, namely the attainment of the end, and this is the "aurea." Secondly, from the very genus of the act which derives a certain praiseworthiness from its due circumstances, from the habit eliciting it and from its proximate end, and thus is due to it a kind of accidental reward which we call an "aureole": and it is in this sense that we regard the aureole now. Accordingly it must be said that an "aureole" denotes something added to the "aurea," a kind of joy, to wit, in the works one has done, in that they have the character of a signal victory: for this joy is distinct from the joy in being united to God, which is called the "aurea." Some, however, affirm that the common reward, which is the "aurea," receives the name of "aureole," according as it is given to virgins, martyrs, or doctors: even as money receives the name of debt through being due to some one, though the money and the debt are altogether the same. And that nevertheless this does not imply that the essential reward is any greater when it is called an "aureole"; but that it corresponds to a more excellent act, more excellent not in intensity of merit but in the manner of meriting; so that although two persons may have the Divine vision with equal clearness, it is called an "aureole" in one and not in the other in so far as it corresponds to higher merit as regards the way of meriting. But this would seem contrary to the meaning of the gloss quoted above. For if "aurea" and "aureole" were the same, the "aureole" would not be described as added to the "aurea." Moreover, since reward corresponds to merit, a more excellent reward must needs correspond to this more excellent way of meriting: and it is this excellence that we call an "aureole." Hence it follows that an "aureole" differs from the "aurea."
Reply to Objection 1. Beatitude includes all the goods necessary for man's perfect life consisting in his perfect operation. Yet some things can be added, not as being necessary for that perfect operation as though it were impossible without them, but as adding to the glory of beatitude. Hence they regard the well-being of beatitude and a certain fitness thereto. Even so civic happiness is embellished by nobility and bodily beauty and so forth, and yet it is possible without them as stated in Ethic. i, 8: and thus is the aureole in comparison with the happiness of heaven.
Reply to Objection 2. He who keeps the counsels and the commandments always merits more than he who keeps the commandments only, if we gather the notion of merit in works from the very genus of those works; but not always if we gauge the merit from its root, charity: since sometimes a man keeps the commandments alone out of greater charity than one who keeps both commandments and counsels. For the most part, however, the contrary happens, because the "proof of love is in the performance of deeds," as Gregory says (Hom. xxx in Evang.). Wherefore it is not the more excellent essential reward that is called an aureole, but that which is added to the essential reward without reference to the essential reward of the possessor of an aureole being greater, or less than, or equal to the essential reward of one who has no aureole.
Reply to Objection 3. Charity is the first principle of merit: but our actions are the instruments, so to speak, whereby we merit. Now in order to obtain an effect there is requisite not only a due disposition in the first mover, but also a right disposition in the instrument. Hence something principal results in the effect with reference to the first mover, and something secondary with reference to the instrument. Wherefore in the reward also there is something on the part of charity, namely the "aurea," and something on the part of the kind of work, namely the "aureole."
Reply to Objection 4. All the angels merited their beatitude by the same kind of act namely by turning to God: and consequently no particular reward is found in anyone which another has not in some way. But men merit beatitude by different kinds of acts: and so the comparison fails.
Nevertheless among men what one seems to have specially, all have in common in some way, in so far as each one, by charity, deems another's good his own. Yet this joy whereby one shares another's joy cannot be called an aureole, because it is not given him as a reward for his victory, but regards more the victory of another: whereas a crown is awarded the victors themselves and not to those who rejoice with them in the victory.
Reply to Objection 5. The merit arising from charity is more excellent than that which arises from the kind of action: just as the end to which charity directs us is more excellent than the things directed to that end, and with which our actions are concerned. Wherefore the reward corresponding to merit by reason of charity, however little it may be, is greater than any reward corresponding to an action by reason of its genus. Hence "aureole" is used as a diminutive in comparison with "aurea."
Source: Summa Theologica (New Advent)