Thomas Aquinas Commentary Lamentations 2:15

"All that pass by clap their hands at thee; They hiss and wag their head at the daughter of Jerusalem, [saying], Is this the city that men called The perfection of beauty, The joy of the whole earth?" — Lamentations 2:15 (ASV)

Here he presents the astonishment of the spectators:

1. Of friends.
2. Of enemies, as in the verse, all your enemies have opened their mouth against you (Lamentations 2:16).

Regarding the first point, the astonishment of compassionate friends is expressed through four signs:

• By the clapping of hands: all they that passed by the way (of your land, seeing the devastation of the land) have clapped their hands.
• By hissing: they have hissed.
• By shaking their heads: and wagged their heads.
• By their words: saying, ‘Is this the city of perfect beauty...’

This was because in matters both spiritual and temporal (for it was a royal and priestly city), it was ‘the joy of all the earth,’ as people came to her from everywhere for the solemn feasts.

With the joy of the whole earth is mount Zion founded, on the sides of the north, the city of the great king (Psalms 47:3).

A populous city, a joyous city (Isaiah 22:2).

And many nations shall pass by this city: and they shall say every man to his neighbor: Why has the Lord done so to this great city? (Jeremiah 22:8).