This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book focuses on theory construction that preserves the integrity of the wholes while abstracting relevant features from them. It also focuses on how psychologists think about complex phenomena. The authors are convinced that a re-analysis of selected ideas from the past of the social sciences helps them in the present. Learning from both successful and failing avenues of theoretical thinking widens the horizon of possibilities for new approaches. The book highlights these ideas of the whole and makes them a fruitful basis for the further advancement of science. The empirically over-flooded social sciences of today are in a deep crisis. The social sciences need theoretical perspectives that simultaneously focus on the whole and its constituent parts. A holistic theoretical system has to include both the presently existing whole parts relations and their potential for transformation into new forms.