With reference to certain metapsychological categories Kuiper demonstrates that a rigid separation into explanatory and understanding approaches is not possible for psychoanalysis if it is to achieve its objectives. In the metapsychological viewpoints, which are formulated in the language of a hydraulic model, life-historical meanings are always implicated in psychoanalytic usage. For instance, one could speak of the viewpoint of relationship and communication instead of the "adaptive" viewpoint; of various intensities instead of the "economical" viewpoint; or of the life-historical instead of the genetic, and so forth.