Thomas Aquinas Commentary Jeremiah 2:20

"For of old time I have broken thy yoke, and burst thy bonds; and thou saidst, I will not serve; for upon every high hill and under every green tree thou didst bow thyself, playing the harlot." — Jeremiah 2:20 (ASV)

Here, he shows that sin is multiplied by an obstinate mind:

1. Regarding duration: from of old. It is as though he were saying, “From the moment the Law was given.” I have called you a sinner from the womb (Isaiah 48:8). What need is there that we serve him, and what will it benefit us if we pray to him? (Job 21:15).
2. Regarding the number of their misdeeds: on every high hill—on high and beautiful places they would sacrifice to their idols. They have sacrificed upon the mountains, and upon the hills they have reproached me (Isaiah 65:7). High and beautiful places are always dedicated to idols.