  This is an idiosyncratic survey of statistical fluid mechanics centering on
the Hopf functional differential equation. Using the Burgers equation for
illustration we review several functional integration approaches to theory of
turbulence. We notice in particular that some important contributions have been
brought about by researchers working on wave propagation in random media, among
which Uriel Frisch is not an exception. We also discuss a particular
finite-dimensional approximation for the Burgers equation.
