Objection 1. It would seem that the angel does not love God by natural love more than he loves himself. For, as was stated (4), natural love rests upon natural union. Now the Divine nature is far above the angelic nature. Therefore, according to natural love, the angel loves God less than self, or even than another angel.
Objection 2. Further, "That on account of which a thing is such, is yet more so." But every one loves another with natural love for his own sake: because one thing loves another as good for itself. Therefore the angel does not love God more than self with natural love.
Objection 3. Further, nature is self-centered in its operation; for we behold every agent acting naturally for its own preservation. But nature's operation would not be self-centered were it to tend towards anything else more than to nature itself. Therefore the angel does not love God more than himself from natural love.
Objection 4. Further, it is proper to charity to love God more than self. But to love from charity is not natural to the angels; for "it is poured out upon their hearts by the Holy Spirit Who is given to them," as Augustine says (De Civ. Dei xii, 9). Therefore the angels do not love God more than themselves by natural love.
Objection 5. Further, natural love lasts while nature endures. But the love of God more than self does not remain in the angel or man who sins; for Augustine says (De Civ. Dei xiv), "Two loves have made two cities; namely love of self unto the contempt of God has made the earthly city; while love of God unto the contempt of self has made the heavenly city." Therefore it is not natural to love God more than self.
On the contrary, All the moral precepts of the law come of the law of nature. But the precept of loving God more than self is a moral precept of the law. Therefore, it is of the law of nature. Consequently from natural love the angel loves God more than himself.
I answer that, There have been some who maintained that an angel loves God more than himself with natural love, both as to the love of concupiscence, through his seeking the Divine good for himself rather than his own good; and, in a fashion, as to the love of friendship, in so far as he naturally desires a greater good to God than to himself; because he naturally wishes God to be God, while as for himself, he wills to have his own nature. But absolutely speaking, out of the natural love he loves himself more than he does God, because he naturally loves himself before God, and with greater intensity.
The falsity of such an opinion stands in evidence, if one but consider whither natural movement tends in the natural order of things; because the natural tendency of things devoid of reason shows the nature of the natural inclination residing in the will of an intellectual nature. Now, in natural things, everything which, as such, naturally belongs to another, is principally, and more strongly inclined to that other to which it belongs, than towards itself. Such a natural tendency is evidenced from things which are moved according to nature: because "according as a thing is moved naturally, it has an inborn aptitude to be thus moved," as stated in Phys. ii, text. 78. For we observe that the part naturally exposes itself in order to safeguard the whole; as, for instance, the hand is without deliberation exposed to the blow for the whole body's safety. And since reason copies nature, we find the same inclination among the social virtues; for it behooves the virtuous citizen to expose himself to the danger of death for the public weal of the state; and if man were a natural part of the city, then such inclination would be natural to him.
Consequently, since God is the universal good, and under this good both man and angel and all creatures are comprised, because every creature in regard to its entire being naturally belongs to God, it follows that from natural love angel and man alike love God before themselves and with a greater love. Otherwise, if either of them loved self more than God, it would follow that natural love would be perverse, and that it would not be perfected but destroyed by charity.
Reply to Objection 1. Such reasoning holds good of things adequately divided whereof one is not the cause of the existence and goodness of the other; for in such natures each loves itself naturally more than it does the other, inasmuch as it is more one with itself than it is with the other. But where one is the whole cause of the existence and goodness of the other, that one is naturally more loved than self; because, as we said above, each part naturally loves the whole more than itself: and each individual naturally loves the good of the species more than its own individual good. Now God is not only the good of one species, but is absolutely the universal good; hence everything in its own way naturally loves God more than itself.
Reply to Objection 2. When it is said that God is loved by an angel "in so far" as He is good to the angel, if the expression "in so far" denotes an end, then it is false; for he does not naturally love God for his own good, but for God's sake. If it denotes the nature of love on the lover's part, then it is true; for it would not be in the nature of anyone to love God, except from this--that everything is dependent on that good which is God.
Reply to Objection 3. Nature's operation is self-centered not merely as to certain particular details, but much more as to what is common; for everything is inclined to preserve not merely its individuality, but likewise its species. And much more has everything a natural inclination towards what is the absolutely universal good.
Reply to Objection 4. God, in so far as He is the universal good, from Whom every natural good depends, is loved by everything with natural love. So far as He is the good which of its very nature beatifies all with supernatural beatitude, He is love with the love of charity.
Reply to Objection 5. Since God's substance and universal goodness are one and the same, all who behold God's essence are by the same movement of love moved towards the Divine essence as it is distinct from other things, and according as it is the universal good. And because He is naturally loved by all so far as He is the universal good, it is impossible that whoever sees Him in His essence should not love Him. But such as do not behold His essence, know Him by some particular effects, which are sometimes opposed to their will. So in this way they are said to hate God; yet nevertheless, so far as He is the universal good of all, every thing naturally loves God more than itself.
Source: Summa Theologica (New Advent)