These three capabilities would be the selling points, said Crake; but there would be a fourth, which would not be advertised. The BlyssPluss Pill would also act as a sure-fire one-time-does-it-all birth-control pill, for male and female alike, thus automatically lowering the population level. This effect could be made reversible, though not in individual subjects, by altering the components of the pill as needed, i.e., if the populations of any one area got too low.