The psychologists Heinz Heckhausen and Peter M. Gollwitzer described action in four phases. Their model is named after the river Caesar crossed. In the first phase, a person weighs the options. Then the person decides and crosses the Rubicon. The second phase is planning: In der Planungsphase bereitet sich die Person auf das Handeln vor. (In the planning phase, the person prepares to act.) The question is no longer what to achieve, but how. Only the third phase is action. The fourth is evaluation.