Matthew Poole and continuators on Lamentations 3:2

2 He hath led me, and brought me into darkness, but not into light.

Darkness in Scripture (metaphorically taken) signifies Ignorance, Sin and Misery; and Light signifies Knowledge, a state of Grace, or a state of mirth and jollity, they are both here taken in the latter sense, as light is taken, Esther 8.16. Micah. 7.8. Iob 18.5. Psal. 97.11. and also Darkness is used, Ier. 13.16. 2 Sam. 22.29. Prov. 20.19. Ioel 2.2. Ezek. 32.8. the sense is God hath not brought me into a joyful and prosperous, but into a sad and calamitous estate and condition.