Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class heteroarenes
                 Class furans
                   2-methylfuran
                   3-acetyl-2,5-dimethylfuran
                   furan [C4H4O; ~O[CH=CH]2~]