'Dark' in the Bible

And you came near, waiting at the foot of the mountain; and flames of fire went up from the mountain to the heart of heaven, with dark clouds, and all was black as night.

These words the Lord said to all of you together on the mountain, out of the heart of the fire, out of the cloud and the dark, with a great voice: and he said no more; he put them in writing on the two stones of the law and gave them to me.

And after hearing the voice which came out of the dark while the mountain was burning with fire, all the heads of your tribes and your chiefs came to me,

You will go feeling your way when the sun is high, like a blind man for whom all is dark, and nothing will go well for you: you will be crushed and made poor for ever, and you will have no saviour.

Your very life will be hanging in doubt before you, and day and night will be dark with fears, and nothing in life will be certain: