[Life space was defined as] the totality of facts which determine the behavior (B) of an individual (or group/organization) at a certain moment. The … - Kurt Zadek Lewin

One can ask two different kinds of questions with regard to the topics of study in psychology as well as in other sciences. One can ask for the phenomenal characteristics of psychological units or events, for example, how many kinds of feelings can be qualitatively differentiated from one another or which characteristics describe an experience of a voluntary act. Aside from this are the questions asking for the why, for the cause and the effect, for the conditional-genetic interrelations. For example, one can ask: Under which conditions has been a decision made and which are the specific psychological effects which follow this decision? The depiction of phenomenal characteristics is usually characterized as “description”, the depiction of causal relationships as “explanation.”

In psychology one can begin to describe the whole situation by roughly distinguishing the person (P) and his environment (E). Every psychological event depends upon the state of the person and at the same time on the environment, although their relative importance is different in different cases.

A business man once stated that there is nothing so practical as a good theory.