Thomas Aquinas Commentary Lamentations 1:9

"Her filthiness was in her skirts; she remembered not her latter end; Therefore is she come down wonderfully; she hath no comforter: Behold, O Jehovah, my affliction; for the enemy hath magnified himself." — Lamentations 1:9 (ASV)

Here the author describes the progression of sin.

1. First, he presents the blame: her filthiness is her sin; is on her feet refers to her affections, which are poised to advance in sin; and she forgets her end, which is death or divine judgment. In all your works remember your last end, and you shall never sin .
2. Second, he presents the punishment: she is cast down from her state of dignity wonderfully—that is, into extreme misery. Scatter them by your power; and bring them down (Psalms 58:12).
3. Third, he begs for mercy: behold, O Lord, which is a plea for God to look with a feeling of pity. See my humiliation and deliver me: for I have not forgotten your law (Psalms 118:153).