The Perfection of Love of God That Belongs to God Alone
[Having concluded that being perfect in the spiritual life means, first of all, loving God perfectly, and secondly, loving one's neighbor perfectly, St. Thomas will take up each of these in turn. And since perfection consists first of all in the love of God, he first takes up the love of God.]
In each love we find many degrees of perfection. With regard to the love of God, the first and supreme degree of perfection belongs to God alone. [Thomas immediately states the point to be established in this chapter, and will go to explain why it is true.] The mode of perfection is considered both on the side of the one who is loved, and of the one who loves: perfection in loving on the side of the one who is loved, means that he is loved as much as he is lovable; and on the side of the one who loves, perfection means that he loves a thing with his full power. [What does it mean to love a thing perfectly, or completely? Since loving is both a personal act, and has a specific object, we can speak of loving perfectly or completely inasmuch as the love is a personal act, or inasmuch as it is love for a specific object or person.] Now since everything is lovable to the degree that it is good, and God's goodness is infinite, he is infinitely lovable. But no creature can love infinitely, since no finite power can have an infinite act. Therefore God alone, who has as great a power of loving as his goodness is, can love himself perfectly as regards the first way of being perfect.
[In the first sense of loving perfectly, only God is a perfect lover of God; no mere human or angel can love God as much as God deserves love. God, being infinite goodness, deserves infinite love. But any created being, just as it has created and limited being, so it's power and act is limited. Therefore its act of love, even love for God, whom it loves above all else, is limited. God's love is infinite, as his goodness is–in fact God's love is really identical with his goodness.
This chapter is pretty straightforward, at least if we don't get into the question of love of self vs. love of others–whether, e.g., in notion the distinction of persons in the Trinity is essential in order for God's love for God to be the greatest love there is, as some have argued.]