In this article, the author attempts to answer the following questions: What did Frederick Perls adopt from Salomo Friedlaender's work, and what does that mean for Gestalt therapy? What can Friedlaender's concepts of “polarity principle,” “creative indifference,” and “revolution of egoism” tell us today? Together with Kant's “a priori ego,” which was described by Friedlaender in his second major work, The Magical “I” (2015), those concepts yield important impulses for the complex theory of Gestalt therapy and its practice. In this context, the draft of an overall representation of human existence is presented, which could serve as a holistic background for Gestalt therapy. Finally, Kant's philosophy in combination with Gestalt psychology offers a solid base for understanding human reason. The conclusion includes a review of postmodern varieties of Gestalt therapy.