"Almost every species in the universe has an irrational fear of the dark." -The Doctor (Silence in the Library)
Why do we fear the darkness? Obviously, no light means that we can't see any threats coming our way, but it's possible to find a place so secure that you don't worry about the enemy. Personally, I think the fear of the dark comes less from a fear that we can't detect our enemies, and more from a fear that we can't detect our friends. People have all sorts of ways to create safe spaces that no one else can access, ensuring that our enemies can't get to us. But to make a place really secure, one must find a way to exclude others.
I got really lost a little while go, and while I was driving around, scared, confused and wondering when I crossed the town lines, I thought about this issue, mostly because it was dark out when this happened. And I remember that my greatest fear during this time wasn't that I would be attacked, or run into trouble, but the I might never find my way home again.
But then, just as I was giving up hope, I went into a parking lot to ask for directions and found a nice couple, who not only gave me directions, they offered to guide me back the highway. Thank you couple I don't know for reminding me that even in the darkness we can find decent people, to help us find our way home.