There is nothing more practical than a good theory ...

H.J. Eysenck (1987):

"Lewin's statement about the usefulness of a good theory has become famous in psychology, and few would probably disagree with him. However, his statement is more honoured in the breach than the observance; there is little evidence in their actual work that most psychologists pay much attention to theory, and some explicitly disassociate themselves from the search for theory and adopt a Baconian or pre-Baconian, purely inductive approach. ..."