In Zhou Dunyi’s Taiji philosophy, the Taiji symbol signifies the Supreme Ultimate, the fundamental principle that underlies all existence and cosmic transformation. It represents the undifferentiated unity that precedes and generates the dual forces of yin and yang, serving as the primordial source from which all reality emerges. From this Great Ultimate arise movement and stillness, and through these, yin and yang come forth as complementary aspects of a single underlying reality. The symbol thus stands for the basic ordering pattern of the cosmos, not as a concrete thing, but as the metaphysical ground that makes all differentiation and change possible.

At the same time, the Taiji symbol portrays the dynamic process by which reality unfolds. The interplay of light and dark expresses the continuous, cyclical transformation between yin and yang, each containing the seed of the other and never existing in absolute isolation. From their interaction come the Five Phases, and from these, the myriad things of the universe. In this way, the symbol functions as a cosmological diagram, showing how the One becomes the many while never ceasing to be the One.

For Zhou Dunyi, this cosmological vision is inseparable from a moral and spiritual vision. The Taiji is also a normative pattern: its harmonious balance of movement and stillness provides the model for human virtue and self-cultivation. By aligning the heart–mind with the natural harmony of yin and yang, a person learns to embody centrality, clarity, and moral balance. The symbol therefore serves as a guide for ethical life, suggesting that true goodness arises from attunement to the very structure of reality.

Finally, the Taiji symbol stands at the crossroads of Daoist and Confucian thought. It gathers Daoist insights about the Dao, natural spontaneity, and the ceaseless flow of yin and yang, and reframes them through a Confucian concern for moral order and social harmony. In this synthesis, the symbol becomes more than a cosmological image; it becomes a bridge between understanding how the universe unfolds and how a human being ought to live within it.