1. What Is Yi
Yi in Taijiquan refers to two related aspects:
- A mental state that maintains the body—or specific parts of it—in a condition of poised readiness, allowing Relaxation, balance, and responsiveness in any direction.
- A set of mental instructions (or commands) that guide specific muscle groups to Relax or engage, resulting in the initiation or continuation of movement.
When the right mental state is maintained, the body rests in calm readiness. This calm awareness mirrors the Zen spirit—not the alertness of an athlete poised for a starting gun, but a presence free from fixation—allowing the body to respond at any moment to its surroundings.
When Yi functions as a precise mental cue—such as directing a body part to Relax or engage—it demonstrates the practical meaning behind the phrase “Movements are triggered and driven by Yi.”
2. Up
Up is one of the essential Yi in Taijiquan, emphasized in almost every serious study of the art. The mental state of Up feels similar to the poised readiness before heading a soccer ball—an intention set in place, prepared to act.
Maintaining the Yi of Up subtly aligns the upper body, elongates the spine like a hanging rope, and Relaxes the shoulders and hip joints. This mindset extends beyond Taijiquan—whether standing, walking, or sitting, it keeps the spirit elevated and the posture naturally upright.
3. Sit
Sit is another core Yi that represents a subtle mental state—an intention to sit down.
Imagine sitting lightly on a bar stool as a friend approaches, and you intend to stand to greet them. In this mental state, you are neither fully seated nor standing—just lightly touching the stool. This captures the essence of Sit in Taijiquan.
The feeling of Sit permeates various postures, whether your upper body is vertical or leaning forward, cultivating a sense of alignment throughout your upper body. When your weight shifts between your legs, Sit evokes a subtle signal, as if your hips were connected to a smooth, waxy surface, allowing a light, seamless sliding sensation. This helps Relax the hip joints, promoting balance and ease of movement.
4. Lead
Lead is a core Yi that refers to restrained and tentative mental state, expressed through a body part moving slightly ahead of the rest. It applies mainly to the tips of the limbs—especially the hands, fingers, and toes.
Lead can also apply to joints. In stepping, for instance, as the leg rises, the knee leads first—like pulling a turnip from the ground. When placing the foot, the toe leads, followed by the lower leg and thigh, ensuring a smooth transition.
The limbs are not the only parts that can Lead; the back can as well. For example, imagine reclining on a display couch in a furniture store. As you lean back cautiously, fearing it might tip too far, your back guides the rest of your body in a careful, tentative descent. In this case, it is the back that Leads the movement.
5. Sink
Sink is a core Yi that refers to a continuous mental command to Relax a body part so that its muscles—and even its joints—seem to drop gently downward. With deeper Relaxation, the joints feel as though they are loosening, approaching an almost disconnected state. This concept primarily applies to the shoulders.
When combined with Lead, Sink transforms the arms into flexible, relaxed ropes free from unnecessary tension. It releases power trapped in rigid shoulders, prevents the arms from acting independently, and ensures that movements such as pushing are driven by whole-body coordination rather than isolated arm strength.
6. Hang
Hang is core Yi that represents a mental state in which all muscles are imagined to drape loosely from the skeleton—much like clothes hanging on a hanger. Even the internal organs are perceived as gently suspended downward.
Whether in motion or at rest, the Yi of Hang induces full-body Relaxation, allowing poised readiness for fluid movement in any direction.
Usually, the Yi of Hang can be developed more easily as the other core Yi are gradually put in place. It not only incorporates the qualities of the other Yi but also evokes the sensation of all the muscles melting together, transforming the body into a hydraulic system in which pressure generated in one area is fully transmitted to another.
Yi and Posture
Many practitioners pursue so-called posture accuracy, often defined as making their posture resemble that of their instructors. Instructors may adjust students’ positions—raising the hands slightly, extending the arms more, and so on—but simply making these external adjustments can result in rigidity and unnatural movement.
In Taijiquan, posture is merely the expression of Yi. The quality of posture depends on one’s individual physique and the degree of Relaxation achieved. When Yi is present, you are Relaxed and your body rests in calm readiness, allowing each part to hang naturally—free from preconceptions or attempts at imitation.
Imagine posture like trees: whether thick or thin, upright or slanted, with branches spreading wide or staying compact, with leaves dense or sparse, bearing fruit or not—all trees express themselves gracefully and naturally, in a calm readiness for any change in their surroundings. Trees have no preconceptions, nor does anyone teach them how to position themselves.
Note: The content of this page is excerpted from Chapters 14 of Mastering Taijiquan in the Modern Age.
Taijiquan Framework 