One of the most poignantly sad verses I know is Psalm 137:
By the rivers of Babylon, there we sat down, yea, we wept when we remembered Zion.
We hung our harps upon the willows in the midst of it.
For there those who carried us away captive asked of us a song, and those plundered us requested mirth, saying, "Sing us one of the songs of Zion!"
How shall we sing the Lord's song in a foreign land?
If I forget you, O Jerusalem, let my right hand forget its skill!
If I do not remember you, let my tongue cling to the roof of my mouth-- if I do not exalt Jerusalem above my chief joy.
Remember, O Lord, against the sons of Edom the day of Jerusalem, who said, "Raze it, raze it, to its very foundation!"
O daughter of Babylon, who are to be destroyed, happy the one who repays you as you have served us!
Happy the one who takes and dashes your little ones against the rock!
A certain simplicity in the theme-- the sorrow of refugees, captured and taken into exile, longing bitterly for home-- is offset by the unexpected turns the words take. It starts with a bitter irony: their captors ask them to sing one of their native songs. The rhetorical question that follows-- "How shall we sing the Lord's song in a foreign land?"-- carries with it the subtle and profound thought of how joys are connected with one another: the song and the place are tied together. And yet the Jews learned, in their long years of exile, to "sing the Lord's song in a foreign land."