In writing a volume of this kind, one becomes keenly aware
that science is indeed a community of scholars. We stand on the
shoulders of giants, and mistake the broadened vision for our own.
In this instance the giants are Kurt Lewin, George Herbert Mead,
Sigmund Freud, William I. and Dorothy S. Thomas, Edward C.
Tolman, Lev Vygotsky, Kurt Goldstein, Otto Rank, Jean Piaget, and
Ronald A. Fisher. ·From these I learned mainly by reading. There
are others who struggled to teach me, often against resistance. Chief
among them were my first teachers in psychology, Frank S. Freeman,