This book proposes a systematic reconstruction of economic foundations based on Five-Dimensional Ontology (5D-O) and Five-Dimensional Systems Theory (5D-ST). Since Adam Smith, economics has fragmented into competing schools—Classical, Neoclassical, Austrian, Institutional, Keynesian, Evolutionary, and Marxist—each grasping one dimension of the economic system while claiming to comprehend the whole. This fragmentation stems from the lack of a unified ontological framework answering the fundamental question: What is the essence of economic exchange? Five-Dimensional Ontology posits that every existent is a five-dimensional entity comprising Boundary (B), Structure (S), Reserve (R), Direction (D), and Intensity (I). Exchange is not the transfer of goods, but the coupling and synergy of two five-dimensional entities across specific dimensions. The theory introduces three independent synergy coefficients: the internal synergy coefficient κ_internal (product of ten inter-dimensional matching degrees, measuring structural coordination independent of scale), the external synergy coefficient κ_external (product of normalized dimension values, measuring scale and volume), and the inter-entity synergy coefficient κ(E₁,E₂) (measuring coupling compatibility between entities). Building on this ontological foundation, the book constructs a complete paradigm: Five-Dimensional Value Theory (value as synergy increment Δκ generated by coupling), Five-Dimensional Exchange Theory (price as five-dimensional coupling signal), Five-Dimensional Growth Theory (economic growth as continuous enhancement of the global synergy coefficient κ_global), Five-Dimensional Cycle Theory (business cycles as phase transitions of κ), Five-Dimensional Monetary Theory (money as the standardized interface of five-dimensional vectors), and Five-Dimensional Justice Theory (justice as dynamic balance among Pareto efficiency, synergy maximization, and minimum survival thresholds). The framework unifies the contributions of all major economic schools, diagnoses their blind spots through dimensional认领, and provides new analytical tools for enterprise strategy, investment decisions, policy formulation, and global justice.