Thomas Aquinas Commentary Lamentations 1:13

"From on high hath he sent fire into my bones, and it prevaileth against them; He hath spread a net for my feet, he hath turned me back: He hath made me desolate and faint all the day." — Lamentations 1:13 (ASV)

Here he presents the severity of the discipline, in that he educated them like a schoolmaster with harsh punishments.

1. He presents the severity in correcting sins committed: from above, that is, in his high council; he has sent fire of affliction, or literal fire, by which the city and camp were burned; into my bones, that is, into her strongholds and fortifications; and so by painful lashes he has chastised me. And vexation alone shall make you understand what you hear (Isaiah 28:19).
2. He shows severity in providing for the future: he has spread a net, that is, an obstacle by which he diverted them from sin. I will hedge up your way with thorns (Hosea 2:6).
3. He shows severity in withholding the benefits of consolation: he has made me forsaken, as if to say, “He gave no consolation after the lashes,” as a schoolmaster usually does with children. God has brought upon me great mourning .