'Darkness' in the Bible

And the LORD said unto Moses, Stretch out thine hand toward heaven, that there may be darkness over the land of Egypt, even darkness which may be felt.

And Moses stretched forth his hand toward heaven; and there was a thick darkness in all the land of Egypt three days:

And it came between the camp of the Egyptians and the camp of Israel; and it was a cloud and darkness to them, but it gave light by night to these: so that the one came not near the other all the night.

And the people stood afar off, and Moses drew near unto the thick darkness where God was.