  Julian Schwinger began the construction of Source Theory in 1966 in response
to the then apparent failure of quantum field theory to describe strong
interactions, the physical remoteness of renormalization, and the utility of
effective actions in describing chiral dynamics. I will argue that the source
theory development was not really so abrupt a break with the past as Julian may
have implied, for the ideas and techniques in large measure were present in his
work at least as early as 1951. Those techniques and ideas are still of
fundamental importance to theoretical physics, so much so that the designation
``source theory'' has become superfluous. Julian did a great deal of innovative
physics during the last 30 years of his life, and I will touch on some of the
major themes. The impact of much of this work is not yet apparent. (Invited
talk at Washington APS/AAPT meeting)
