  This is a very short presentation regarding developments in the theory of
nuclear many-body problems, as seen and experienced by the author during the
past 60 years with particular emphasis on the contributions of Gerry Brown and
his research-group. Much of his work was based on Brueckner's formulation of
the nuclear many-body problem. It is reviewed briefly together with the
Moszkowski-Scott separation method that was an important part of his early
work. The core-polarisation and his work related to effective interactions in
general are also addressed.
