While rediscovering one molecule in chemical space can require the screening of 10 5-6 ) molecules, finding a molecule with a particular property, such as absorbance at a particular wavelength, can often be accomplished more efficiently since there tends to be many different molecules with the desired property (Figures , and 2b). For example, finding molecules that absorb at 200±7, 400±7, and 600±7 requires the screening of up to 13,000, 120, and 400 different molecules.