You're not afraid of the dark.
You're afraid that in the end, everything you know is as dark and empty as your room at night. Everything you love can vanish and everything you fear can exist. You have no control. In the dark we are vulnerable; in the dark we are alone. We can look no where for comfort. We can only look inside ourselves, but sometimes we are darker and emptier.
You're not afraid of rats.
Every day you shove the filth of life as far away from you as possible. You drop unloved food into trash bags, you flush shit into the under-earth, you wash the sweat that rises up out of your skin. We are the civilized ones and our world is clean and white and put in neat boxes. And what of the rat? You have fed him your whole life. Your bastard child can walk into your home, your clean white box, and your wife still doesn't know. Sometimes you seem to forget.
You're not afraid of dying; you're afraid of the unknown, the end.
You're just afraid.
We all are.