Articles 29-30
In the twenty-ninth and thirtieth article, the question is raised whether the angels neither grieve nor shed tears but nevertheless act like those who do so.
This is necessarily true and it is the teaching of Augustine, who says in De Civitate Dei, bk. 9, ch. 5, The holy angels punish those whom the eternal law of God consigns to be punished while feeling no anger, assist those who are suffering while not feeling compassion, and rescue from peril those whom they love without feeling their fear. And nevertheless, the names of these passions are used by the custom of human speech due to a certain resemblance between our actions and theirs, and not because of the frailty of our own passions.
Chapter 30 of 37