Thomas Aquinas Commentary Jeremiah 6:6-7

"For thus hath Jehovah of hosts said, Hew ye down trees, and cast up a mound against Jerusalem: this is the city to be visited; she is wholly oppression in the midst of her. As a well casteth forth its waters, so she casteth forth her wickedness: violence and destruction is heard in her; before me continually is sickness and wounds." — Jeremiah 6:6-7 (ASV)

Here, the prophet speaks of the cause of the siege—namely, the sin that caused it. He makes three points concerning this.

1. He speaks of their universal wickedness: this is the city of visitation, meaning it is a city deserving of judgment; every cunning device, every kind of trickery. Usury and fraud have not failed from her streets (Psalms 54:11).
2. He speaks of the hardness of their hearts: as a cistern cools her water and keeps it untouched by the heat. As it says above: they have dug for them broken cisterns, which are not able to hold water (Jeremiah 2:13).
3. He speaks of the continuation of their sin. Iniquity: wasting and destruction are in their ways; they have not known the way of peace (Isaiah 59:7–8). Sickness, as if it were a punishment corresponding to the two sins mentioned above.