There is a moment, however, in the centre of the book, where the darkness lifts. It is a fleeting glimpse of light, but stands out all the more for that: "The steadfast love of the Lord never ceases; his mercies never come to an end; they are new every morning; great is your faithfulness".
Because of God's character, there is hope. Specifically, because God's mercies are new every morning, yesterday does not determine today, and today does not irrevocably set the course of tomorrow. Jerusalem's fall, and Judah's sin which prompted it, does not rule out future intervention by the God of grace. It does not rule out new mercy, and a morning of light.
And yet the book ends in another moment, the darkest moment in the whole Old Testament: "Restore us to yourself, O Lord, that we may be restored! Renew our days as of old - unless you have utterly rejected us, and you remain exceedingly angry with us".
The prophet ponders the darkest possibility. What if there is no new mercy? What if God has utterly rejected his people - as indeed their conduct fully deserves?
The two moments are related. Because God's mercy is new every morning, it cannot be presumed upon, but must be actively sought out, trusted, and received with each new day. The lament shows that the author, at least, has learnt the hard lesson of the fall of Jerusalem: past mercy does not provide present security. (Think of the cry of those who were confident that Jerusalem would never fall: "The temple of the Lord, the temple of the Lord!" They knew that in the past God had chosen this place, and they assumed that this past mercy guaranteed their security and blessedness in the here and now, no matter their behaviour or their present attitude to God).
How often do I fail to seek new mercy each day?