 Wolff’s distinction between empirical and rational psychology proved to be enormously consequential, but no less important (if less well attended to) is the fact that these disciplines remain intrinsically connected. For Wolff, the observations catalogued in the course of empirical psychology serve as principles for the inferences of rational psychology, and the resulting findings on the part of rational psychology serve to guide our empirical observation in search of confirmation. Thus, Wolff writes, that which everyone can experience of themselves will serve “as a principle for deriving something else that not everyone can immediately see for themselves” (GM: §191), and that which is known of the soul from experience “is the touchstone [Probier-Stein] of that which is taught [in rational psychology] of its nature and essence” (GM: §727). Rather than constituting distinct disciplines, empirical and rational psychology amount to complementary parts of a single science, working together in the same way in which observation and theory co-operate in astronomy (EP: §5). Consequently, Wolff’s rational psychology is not to be identified as a narrowly rationalistic psychology, insofar as the latter is taken to intend a science of the soul that proceeds completely independently of experience. Nor is this interdependence of the two parts of psychology an aberration as Wolff takes their union as exemplifying his ideal for science of a connubium rationis et experientiae (EP: §497; cf., Dyck 2014, Rumore 2018).