Measuring against the exchange of ideas between Chinese and Western heterogeneous cultures, the Catholic "theory of soul" disseminated by the Jesuits in Late Ming must locate appropriate topographies of thoughts in order to inculturalize and thus to convince Chinese Confucians. This article focuses on Giulio Aleni's A Brief Introduction to the Study of Human Nature (Xingxue Cushu), analyzes how he adapts to Neo-Confucianism and uses "spiritual nature" to explicate Catholic "soul (anima)," and compares Catholic "theory of soul" with Neo-Confucianism's "theory of human nature" to enlighten their similarities and differences. Although "spiritual nature" is identified with "soul," and is thus inevitably suspected of a conceptual analogical interpretation (geyi), it exhibits the possibility for the Neo-Confucian theory of human nature (the theory of mind and nature) to provide theoretical resources for the inculturation of Catholic theology and philosophy.