Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       Astra Plinius - celestial bodies
         Universe
           (Supercluster) Virgo-Hydra-Centaurus Supercluster
             (Supercluster) Virgo Supercluster
               (Cluster) Local Group
                 (Galaxy) Milky Way Galaxy veter.
                   (Spiral arm) Sagittarius Arm
                     5500 (Bright nebula) M17 (Sgr) - Omega Nebula
                     7000 (Bright nebula) IC 4703 (Ser)