Taijiquan consists of three elements:
1. The tangible physical activities that are visible to an onlooker. When the body is sufficiently trained to express synchronisation of the upper and lower body, coordination of opening and closing movements, and accuracy of the energy route. When there is movement coordination of the hands and feet, elbows and knees, shoulders and hips, it is termed as the '"three external harmonies".
2. The mental and psychogenic activities that are not clearly visible and hidden in the heart and mind, but plays the vital role of commanding and influencing the physical activities.
3. Qi and blood that flow within the body along the meridians. This is driven by the combination of physical activities and mental and psychogenic activities. Through repeated and focused training, using the heart/mind to lead intention that in turn lead the qi/energy, that in turn guides the correct movements.
When all three elements are realised and are executed seamlessly, when the heart and intention, Intention and energy, energy and body shape are fully coordinated, it is known as the "three internal harmonies".
In fact, the three elements are mutual conditions that require simultaneous execution that cannot be separated. Separation in narratives is in order to enable understanding of the principle.