the lightning flashed and then the people danced

Isaiah was a prophet of God. He talks of God's sword, the swift and turning leviathan in the beginning of the 27th chapter. It seems out of context. Here they are, a warning in the air, the blood of the earth will be revealed and God will use a sword named leviathan and then there will be party hearty in the vineyard...oh wait, with his sword he will chase down and slay leviathan.

It's funny sometimes how I misunderstand. I started with the NIV and couldn't figure out why the other versions all seemed to contradict it. Then, with a better translation in hand, the NIV seems to be fine after all. It's just me, as usual.

No frolicking in Isaiah, just dying. Leviathan here seems to represent evil for some reason.