Thomas Aquinas Commentary Lamentations 2:21

"The youth and the old man lie on the ground in the streets; My virgins and my young men are fallen by the sword: Thou hast slain them in the day of thine anger; thou hast slaughtered, [and] not pitied." — Lamentations 2:21 (ASV)

Here, the author presents the universal nature of the punishment, and he does so in three parts.

1. He presents the punishment as common to all: the child and the old man lie, dead or fallen; without, that is, in the streets or outside the city. With you I will break in pieces the old man and the child, the young man and the virgin (Jeremiah 51:22).
2. He shows the indignation of the one who punishes: you have slain, by your authority, although by the hand of the Chaldeans. I have trampled on them in my indignation, and have trodden them down in my wrath (Isaiah 63:3).
3. He excludes mercy: you have killed, and shown them no pity. I will kill and I will make to live (Deuteronomy 32:39). He strikes, and his hands shall heal; in six troubles he shall deliver you, and in the seventh, evil shall not touch you (Job 5:18–19).