Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies "crystal-kingdom" chemical substances chemical compounds Class carbohydrates [Cn(H2O)n, etc.] Class saccharides Class monosaccharides - sugars Class aldoses [H[CH(OH)]nC(=O)H (n>=2), etc.] ribose [C5H10O5; CH(=O)[CHOH]3CH2OH]