  The organizers of the Memorial Session for Herman Rietschel asked that I
review some of the history of the interplay of superconductivity and spin
fluctuations. Initially, Berk and Schrieffer showed how paramagnon spin
fluctuations could suppress superconductivity in nearly-ferromagnetic
materials. Following this, Rietschel and various co-workers wrote a number of
papers in which they investigated the role of spin fluctuations in reducing the
T_c of various electron-phonon superconductors. Paramagnon spin fluctuations
are also believed to provide the p-wave pairing mechanism responsible for the
superfluid phases of $^3He$. More recently, antiferromagnetic spin fluctuations
have been proposed as the mechanism for d-wave pairing in the heavy-fermion
superconductors and in some organic materials as well as possibly the high T_c
cuprates. Here I will review some of this early history and discuss some of the
things we have learned more recently from numerical simulations.
