Surrender the mind to the Heart.

Contrary to popular belief, Taijiquan 太極拳 (Tai Chi) is never about the form. It is all about the state, the state of Taiji, or ultimate polarity (Yin and Yang). When the polarities of Heaven and Earth are properly rooted, something in between begins to flow. That flow is the life-force energy that can nourish, heal, or even affect other people, hence the martial application.

Training Taiji, and any internal arts, initially requires an understanding training partner to validate the internal state that would manifest in the physical. Once the practitioner can remember the feeling of the internal state, they can then practice solo, first without movement, then later a series of movements can be added. Hence the form.

The form is always optional, but it's still a good, joyful activity that reminds the body of the internal Taiji state when there is no training partner at hand.