10 Days of darkness is symbolic to 3 days of darkness in the heart of the earth. It's when most gave up. Lost hope and some threw in the towel. You are learning biblical lessons here whether you realize it or not. All part of the plan.
"For as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth."
Matthew 12:40