  Critical points of a master function associated to a simple Lie algebra \g
come in families called the populations [MV1]. We prove that a population is
isomorphic to the flag variety of the Langlands dual Lie algebra \g^t. The
proof is based on the correspondence between critical points and differential
operators called the Miura opers.
  For a Miura oper D, associated with a critical point of a population, we show
that all solutions of the differential equation DY=0 can be written explicitly
in terms of critical points composing the population.
