'Dark' in the Bible

To get the sense of wise sayings and secrets, and of the words of the wise and their dark sayings.

Who give up the way of righteousness, to go by dark roads;

The way of sinners is dark; they see not the cause of their fall.

At nightfall, in the evening of the day, in the black dark of the night.

Who says, Oh! who says, Ah! who has violent arguments, who has grief, who has wounds without cause, whose eyes are dark?