Thomas Aquinas Commentary Lamentations 2:9

"Her gates are sunk into the ground; he hath destroyed and broken her bars: Her king and her princes are among the nations where the law is not; Yea, her prophets find no vision from Jehovah." — Lamentations 2:9 (ASV)

Here he weeps over the destruction of people, considering three groups:

1. Those whose misfortune is more intensely miserable according to the degree of their dignity.
2. Those whose misfortune is miserable out of respect for their status: the ancients sit upon the ground, they have held their peace (Lamentations 2:10).
3. Those whose misfortune is miserable because of their youth: my eyes have failed with weeping (Lamentations 2:11).

Concerning the first point, he makes two observations.

First, regarding the temporal princes, he uses a parable or metaphor: her gates are sunk into the ground; that is, they have been so wrapped up in tribulations that they cannot easily escape. As the psalm says, I stick fast in the mire of the deep: and there is no sure standing (Psalms 68:3). Her gates represents kings, to whom the power of judgment belonged, which was exercised at the gates; he has destroyed by capturing, and broken by leading into captivity, her bars, the princes by whom the kingdom was strengthened, as a door by its bars.

And he explains: her king and her princes are in the gentiles, that is, among the Gentiles. He has broken gates of brass, and burst the iron bars (Psalms 106:16). Her gates shall lament and mourn, and she shall sit forsaken on the ground (Isaiah 3:26).

Second, regarding the spiritual princes, namely, the priests: the law is no more, to be taught by the priests. The lips of the priest shall keep knowledge, and they shall seek the law at his mouth (Malachi 2:7). And concerning the prophets: and her prophets have found no vision from the LORD. There is now no prophet: and he will know us no more (Psalms 73:9).