We live out our lives between verses 3 and 4 of the 126th Psalm.
Verse 3 is the conclusion of a song describing the time when God changed Zion’s circumstances for the better. The reader should probably be thinking of the return from exile under the Persian Empire to rebuild the temple, but echoes of the Exodus and of any other time when God’s people were saved from trouble are appropriate here too.
This song must be intentionally generic in order to engage the whole history of Israel, and to engage the even the contemporary reader thousands of years later - it should call to your mind a time when all seemed lost, but when God came through for you in a way that felt like a dream.
When God acted in this way, trouble was replaced by laughter and joyful shouts, and the excited notice of bystanders (the nations in v. 2), a notice with which verse 3 heartily agrees - “Yes, the LORD has done great things for us, and we are overjoyed” (Psa 126:3 CEB). The psalmist - and the reader recalling her own joy - is overjoyed because of the LORD having changed circumstances for the better, because the LORD has done great things.
Something changed, God did it, and it was really really good; it made a real difference.
Verse 4 comes next, and should just about you whiplash if you’re paying attention. In the first 3 verses, "the LORD changed Zion’s circumstances for the better” (v. 1) leading to “and we are overjoyed” (v. 3). Verse 4 cuts in the opposite direction, changing from rejoicing and praising back to petitioning: "LORD, change our circumstances for the better, like dry streams in the desert waste!”
The LORD has changed circumstances, but apparently there are yet more circumstances in need of changing. Our world in some ways still resembles dry streams in the desert waste. But what follows verse 4 isn’t a hopeless wallowing in that desert waste, but a hopeful and expectant planting. God has moved and objectively changed things for his people. God’s people expect him to do so again.
And so the psalm closes with an agricultural image. In memory of the dream of changed circumstances past, there in the midst of the lifeless desert waste, God’s people plant seeds. Verses 5 and 6 are in parallel - both start with sadness and planting, and move to joyful shouts and an abundant harvest. We look all around us, and all we see is desert waste. And yet, right there, in the midst of our tears in that wasteland, we plant seeds. And we do so in the expectant hope that even here in the desert God will see to the harvest.
All is not yet fully well. God has saved in the past, and what joy that brought, but God’s people still need some saving in the present. We remember what God did, and we pray for God to do yet more. It is that space, the space between memory and hope, between faith and expectation, in which we live out our lives under the sun.