There is no amount of darkness that can extinguish the inner light. The important thing is not to spend our lives trying to control the environment around us. The task is to control the environment within us.
faith isn't faith until it's all we have to hold on to and knowledge fails us. When we pray for faith, we automatically pray for darkness. Think about it.
Hope grows in us, despite our moments of darkness, regardless of our regular bouts of depression.