Abstract: As an important development philosophy, "investment in people" thoroughly breaks through the constraints of the traditional growth logic of "investment in things". Oriented toward the improvement of human capabilities, cultivation of personal qualities, shaping of values and all-round development of individuals, it serves as the core driving force and fundamental support for achieving common prosperity in people's spiritual life. Transcending the traditional logic of "investment in things" and the external supply paradigm, "investment in people" establishes its theoretical foundation on 5 internal logics: the overarching guidance from "putting people first" to "spiritual fulfillment,"the core foundation from passive reception to active creation, the operational hub from supply-demand mismatch to precise matching, the baseline safeguard from unequal opportunities to universal sharing, and the long-term destination value from external empowerment to endogenous consciousness. It achieves an organic integration ranging from value guidance and subject activation to supply-demand matching, fairness guarantee, as well as external empowerment and endogenous consciousness, thereby consolidating the theoretical foundation for common prosperity in spiritual life. At the practical level, it relies on the coordinated operation of 5 major mechanisms --- capability generation, resource supply, value guidance, inclusive sharing and circular enhancement --- to consolidate the endogenous foundations, optimize resource allocation, build ideological consensus, uphold the baseline of fairness, and establish long-term momentum. It promotes the transformation of spiritual-ethical advancement from a "blood-transfusion" supply model to a "blood-generation" empowerment model, from cultural distribution to mass creation, from hardware input to competency cultivation, and from partial coverage to universal sharing. In the context of the "15th Five-Year Plan" period, embedding the philosophy of "investment in people" throughout the whole process of advancing common prosperity in spiritual life will help promote the coordinated development of material and spiritual civilization and foster people's all-round development. It also provides theoretical support and practical paths for solidly advancing common prosperity and Chinese modernization.

Key words: investment in people, common prosperity in spiritual life, all-round development of human beings, "the 15th Five-Year Plan", Chinese modernization