'Dark' in the Bible

Your eye is the lamp of the body. When your eye is sincere, your whole body is full of light also. But when it is evil, your body [is] dark also.

If therefore your whole body [is] full of light, not having any part dark, it will be completely full of light, as when the lamp with [its] light gives light to you."

Therefore everything that you have said in the dark will be heard in the light, and what {you have whispered} in the inner rooms will be proclaimed on the housetops.