In other words, regardless of the path, the Tai Chi stage required one to pass through the Three Lives Stage, condensing a Rune Core and three Rune Branches.
The reason Tai Chi was also known as Foundation Establishment was because this entire stage was dedicated to forging one's Dao Foundation.
In the Tai Chi Three Lives stage, four specific Techniques became the foundation of one's cultivation.
The Rune Core served as the main trunk, and the Three Lives Rune Branches were the sprouts, together forming the seedling of a basic 'Skill Tree'.
As for advancing to Duality, the first step required selecting one of the Three Lives Runes to undergo the First Transition.
In layman's terms, it was like choosing a "sprout" to make the Skill Tree grow and sprout branches. This was why the Three Lives Runes were also called Branch Runes.
