The word 理性 is formed through the conceptual merging of its two component characters: 理, which represents the inherent order, pattern, or principle of things (like the grain in wood or the reason in an argument), and 性, which denotes innate character, nature, or essence. Together, they construct the abstract notion of "rationality" by positing that the fundamental nature (性) of proper thought or judgment is to align with and be guided by objective principle and logical order (理). Thus, the term embodies the idea that reason is the essential quality of engaging with the world through its underlying principles.