  We present a fairly new and comprehensive approach to the study of stationary
flows of the Korteweg-de Vries hierarchy. They are obtained by means of a
double restriction process from a dynamical system in an infinite number of
variables. This process naturally provides us with a Lax representation of the
flows, which is used to find their bi-Hamiltonian formulation. Then we prove
the separability of these flows making use of their bi-Hamiltonian structure,
and we show that the variables of separation are supplied by the Poisson pair.
