'Dark' in the Bible

He is the unveiler of deep and secret things: he has knowledge of what is in the dark, and the light has its living-place with him.

Because a most special spirit, and knowledge and reason and the power of reading dreams and unfolding dark sayings and answering hard questions, were seen to be in him, even in Daniel (named Belteshazzar by the king): now let Daniel be sent for, and he will make clear the sense of the writing.

And in the later years of their kingdom, when their evil doings have become complete, there will come up a king full of pride and expert in dark sayings.