Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class acylals [R2C[OC(=O)R]2] - diesters of geminal diols
                 benzylidene diacetate [PhCH[OC(=O)CH3]2]