Explanations in social theories can be idiographic or nomothetic. Windelband is now mainly remembered for the terms "nomothetic" and "idiographic", which he introduced. Behavioral activation (BA) is an idiographic and functional approach to depression. FAP is an idiographic (as opposed to nomothetic) approach to psychotherapy. It integrates idiographic pictures basing on its source and constitution. Gordon Allport (1937) described two major ways to study personality&colon; the nomothetic and the idiographic. This is an idiographic method that is used to help examine inner experiences. "Idiographic psychology" is an attempt to understand the unique aspects of a particular individual.