Lamentations 5:18

For the mountain of Zion, which is desolate,

The jackals walk on it.

Capping all that has gone before was the fact that the mountain of Zion, that mountain that had once throbbed with the sound of worshippers walking in and around the Temple, was now desolate. It had become the haunt and walking place of jackals. Outwardly it looked as though YHWH was no longer interested in the land, or in His people.

Lamentations 5:19

You, O YHWH, abide for ever,

Your throne is from generation to generation.

But the prophet knew differently. The Temple site may be desolate, the Temple might lie in ruins, but he knew that YHWH sat on His throne for ever. For His throne was an eternal throne, surviving from generation to generation. Here was the climax of the lament, the certainty that, despite all that had happened and all the gloom and misery, YHWH was on His throne. And if that were so nothing else was of comparative importance.