The Heian period (794-1185) is often associated with rampant meta-physical forces, such as vengeful spirits (onryō 怨霊), which represented the consequences of political manoeuvrings and intrigue in the form of bodily retribution through illness. It has been overlooked, however, that beliefs in such transcendent entities constituted a central aspect of the era’s cosmology and served to define the political relations between the dominant elites in power. The main aim of this thesis is to illustrate the epistemological and socio-political significance of metaphysical beliefs for the Heian-period worldview and the organisation of the body politic. The focal point of this study is the formulation of the episteme as an underlying structure that generated interpretative patterns based upon which the meta-physical beliefs constituted part of an explanatory paradigm. By inserting this abstract structure, it becomes possible to examine the plethora of beliefs on one level, regardless of the traditions they stemmed from, and avoid discussions concerning the applicability of the term “religion”. This approach thus enables an unconstrained evaluation of their functions, as they can be deduced from their application to certain situations and their portrayal in the sources. To that end, this thesis adduces a variety of kanbun documents from the mid- to late Heian period, which span the height of Fujiwara dominance, their decline, and the subsequent ascendency of the retired emperors (hōō 法皇). The political climate of this time span is particularly conducive to an in-depth understanding of meta-physical beliefs, since their use became highly politicised. Based on a selection of four ambiguous keywords, namely mononoke 物気, jaki 邪気, mokke 物怪, and tatari 祟, I will demonstrate that the meta-physical realm was arranged taxonomically and that the discourse relating to such beliefs was remarkably restrictive, as it mirrored the configuration of the bureaucracy. In other words, the transcendent realm added a further dimension to the articulation of political and social relations, as it delineated the groupings of the dominant agents and determined which aspects of the meta-physical discourse they could draw upon for explanations according to their positions. It has emerged from the collected data that in the specific context of communication between the transcendent and mundane realms, a conscious distinction was made between the emperor and his meta-physical discourse and those sets of beliefs that were utilised by other elite groups. Beginning with an examination of the keywords and what they reveal about the composition of Heian-period cosmology, I set forth the distinctions made between various categories and the principles by which they were organised. These differentiations are particularly prominent in the ritual context, which provides an indication of how the episteme could be manipulated to serve socio-political ends. Such objectives often represented affiliations between important personages and ritual institutions that had seemingly been neglected by the centre. The attempts made to communicate with the meta-physical realm further confirm the intrinsic link between beliefs in transcendent entities as explanatory tools, socio-political concerns, and the centrality of the jingi 神祇 cult for the position of the ruler. With this thesis I hope to provide new insights into the pre-modern episteme in relation to socio-political dynamics.