The profession of nursing searches for a theory base for its practice, but there are problems inherent in defining the nature of concepts and in building them into testable hypotheses and theories. Some concepts are derived from everyday experience, some from the conventional wisdom of the profession. Some are developed by deductive methods from related sciences, some inductively from nursing practice itself. Although a few embryonic theories have been developed, little has been developed at the prescriptive level nor has any unifying model satisfied all thinkers. For the present there is a need to isolate concepts from conventional professional wisdom, for factor isolating research, for the testing of hypotheses against nursing practice.