Isaiah 3 promises “comfort” for barren, bereft mother Zion. Comfort isn’t just soothing pain, but a change of condition. Yahweh brings comfort because He brings justice, establishing righteousness. The comfort is spelled out in a lovely list:
From her wilderness as Eden
From the Arabah as the garden of God
Joy and gladness will be found in her
Thanksgiving and the voice of melody.
A fourfold comfort, a comfort as extensive as the four-cornered land itself. But the last two items on the list are themselves a list of four: joy, gladness, thanksgiving, voice of melody. Joy and gladness spread out in song to the four corners: Eden restored is a soundscape.
Put all this together, and you get a six: Eden, garden, joy, gladness, thanks, voice of melody. It is a sixfold renewal of Eden, the creation of the sixth day.