Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             reactive intermediates
               Class radicals [X•]
                 1 Class alkyl radicals [CnH2n+1•]
                 2.1 Class aminyl radicals [R2N•]
                 2.2 Class aminoxyl radicals [R2NO• <-> R2N•+-O]
                 2.3 Class iminoxyl radicals [R2C=NO•]
                 3 Class sulfenyl radicals [RS• (R≠H)]