The term taijitu in modern Chinese is commonly used to mean the simple "divided circle" form (☯),
but it may refer to any of several schematic diagrams that contain at least one circle with an inner pattern of symmetry representing yin and yang.
Non-polar (wuji) and yet Supreme Polarity (taiji)!
The Supreme Polarity in activity generates yang; yet at the limit of activity it is still.
In stillness it generates yin; yet at the limit of stillness it is also active.
Activity and stillness alternate; each is the basis of the other.
In distinguishing yin and yang, the Two Modes are thereby established.
The alternation and combination of yang and yin generate water, fire, wood, metal, and earth.
With these five [phases of] qi harmoniously arranged, the Four Seasons proceed through them.
The Five Phases are simply yin and yang; yin and yang are simply the Supreme Polarity;
the Supreme Polarity is fundamentally Non-polar.
[Yet] in the generation of the Five Phases, each one has its nature.
Instead of usual Taiji translations "Supreme Ultimate" or "Supreme Pole",
Adler uses "Supreme Polarity" (see Robinet 1990)
because Zhu Xi describes it as the alternating principle of yin and yang, and:
insists that taiji is not a thing (hence "Supreme Pole" will not do).
Thus, for both Zhou and Zhu, taiji is the yin-yang principle of bipolarity,
which is the most fundamental ordering principle,
the cosmic "first principle." Wuji as "non-polar" follows from this.
Since the 12th century,
there has been a vigorous discussion in Chinese philosophy
regarding the ultimate origin of Zhou Dunyi's diagram.
Zhu Xi (12th century)
insists that Zhou Dunyi had composed the diagram himself,
against the prevailing view that he had received it from Daoist sources.
Zhu Xi could not accept a Daoist origin of the design,
because it would have undermined
the claim of uniqueness attached to the Neo-Confucian concept of dao.