Chasing Windmills X - Doors That Open

Doors that open sideways
Doors that open eyes
Doors that open easily
Doors that open lives
Doors that open to the unknown
Doors that open within
Doors that open to the beginning
Doors that open to the end
           Are all but doors that open
             So what of those that don't?
               We've been told to forget them,
                 But I've made sure I won't.