'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.

forasmuch as an excellent spirit, and knowledge, and understanding, interpreting of dreams, and showing of dark sentences, and dissolving of doubts, were found in the same Daniel, whom the king named Belteshazzar. Now let Daniel be called, and he will show the interpretation.

And in the latter time of their kingdom, when the transgressors are come to the full, a king of fierce countenance, and understanding dark sentences, shall stand up.