Abstract: Private law theory is pulled in opposite directions: internal and external perspectives on law; holistic and reductionist methodologies; conceptualist and nominalist views; and deontological and consequentialist approaches. Relatedly, theories tend to focus on the micro or the macro scales – interpersonal relations or societal effects – but face difficulties in connecting them. In this paper, we examine these problems in private law theory through the lens of the legal phenomenology of Adolf Reinach. According to Reinach, the law presupposes a realm of real, timeless entitles and their workings that are synthetic a priori: they are neither conventional nor contingent. Nor are they inherently moral or customary. We argue that regardless of the ontological status of what Reinach identifies as a priori, it points toward something more robust than most current theories would countenance. We illustrate the usefulness of this perspective through Reinach’s analysis of property, transfer, and representation. Reinach captures features and generalizations that have eluded analysis, as, for example, when he treats the principle of nemo dat quod non habet (‘one cannot transfer what one does not own’) as underlying all transfer even if displaced by positive rules such as good faith purchase. His views also point toward the importance of accessibility for legal concepts, including cases of tacit knowledge. Whatever its exact source, this “deep structure” of the law has the potential to partially reconcile some of the fissures in private law theory and to connect the micro and the macro through a better understanding of system in law.