'Dark' in the Bible

and they entered into a boat, and were going over the sea unto Capernaum. And it was now dark, and Jesus had not yet come to them.

These things have I spoken unto you in dark sayings: the hour cometh, when I shall no more speak unto you in dark sayings, but shall tell you plainly of the Father.

His disciples say, Lo, now speakest thou plainly, and speakest no dark saying.

Now on the first day of the week cometh Mary Magdalene early, while it was yet dark, unto the tomb, and seeth the stone taken away from the tomb.