Wuji is called Non-polar or "without ridgepole" because it is the vacuum created by disactivating the opposing effect of yin. In Chinese, Wuji means boundless and infinite. A very important English translation of wuji is limitless.
Wuji is described as "ultimate of nothingness" because it is an empty space that has no limit or boundary.
Taiji is the "Supreme Ultimate" and Wuji is the "Ultimateless," which means Wuji is inferior to Taiji.
In the past, Wuji was the contrast of Taiji. Today, Wuji is nothing, null and void. Irrational superstitious, mystical and diabolical elements occupied Wuji and desperately and forcefully opposed Taiji.
Taiji is reasoning and Wuji was superstition and mysticism. Wuji and Taiji were animal sacrifice (the beast) and a fire placed on an altar. The altar was Bagua.
Bagua was polarised into two opposing extremes Yin and Yang while the beast was still on the altar. During this period the beast dominated and governed the universe.
Then, reasoning came, the fire was ignited, and the beast was offered as a burnt sacrifice to God. Wuji transformed into an empty space the moment the beast was consumed by the flame.
Taiji became the only pole and Wuji became non-polar the moment the beast was eliminated completely from the altar.
The fire is the triumph of reasoning over diabolism in religions, divining and things used for divination. It is sanitising and purifying the system through education.
Rather than be an opposing force, Wuji is the eternal emptiness, null, and void prior to Taiji. It was the mystical and superstitious old world destroyed by the fire of reasoning. This explains why Wuji (an empty space) is called the premordial universe prior to Taiji (the new universe).
Wuji and Taiji are the two digits in binary numbers. Wuji is 0, Taiji is 1, and the sum of Wuji and Taiji is equal to 1 (Taiji). 0 comes before 1.