These two verses complete the literary parallels introduced by the “day of the Lord,” continuing the theme of the destruction of the wicked.
Literature: The darkness in verse 10 may have a physical component when the world ends, but it is also a literary device presaging the spiritual darkness described in verse 11. Verse 10 contrasts natural darkness with natural light. Those entities that ought to give light are dark. This is a poetic reversal of the natural order. Similarly, the social order, in which the wicked reign, is also reversed; they are brought down, and the mighty are humbled.