Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class arsines [R3As]
                 1 "arsine"ᵀ [AsH3]
                 2 primary arsines [RAsH2 (R≠H)]
                 3 secondary arsines [R2AsH (R≠H)]
                 4 tertiary arsines [R3As (R≠H)]