From the Explanation of the Method of Taiji (Taiji fashuo), text 8
The body, the waist and the crown of the head, how can you not pay attention to them?
If one of it is lacking, you waste your gongfu (your time and hard work).
The waist and the crown of the head can be studied a lifetime.
If the body follows my wishes, I can extend and relax.
If you give up this truth, what can you finally reach?
After ten years you will still be confused.
Translation by Freya and Martin Boedicker