Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class thiocarboxylic acids
                 1 Class monothiocarboxylic acids [RC(=O)SH or RC(=S)OH]
                 2 Class dithiocarboxylic acids [RC(=S)SH]