The progression of Taijiquan practice can be seen in this way: in the first stage practice is like moving at the bottom of water; in the second stage it is like moving in water; and in the third stage it is like moving above water. This represents the progression of Taijiquan from substantial to insubstantial. In the beginning the practice is focused upon weightedness and substantiality. As skill increases movements become insubstantial- light and agile - until movements ...appear to glide in the wind.
Practising at the bottom of water the feet constantly seek the ground. When the body moves the water resistance is constantly felt. As one progresses and the body starts to move in the middle of the water, the feet do not need to seek the ground at the bottom and the resistance of the water become lesser; until the third stage when movements are above the water and resistance from the water is no longer felt. The body is extremely light and agile. The expression of Taijiquan is “vacuous, loose, whole, alive”. How does one achieve this? Taijiquan demands that in training movement principles, begin from denseness-heaviness towards lightness-agility. People achieve this in different degrees through their lifetime training.
The Taijiquan principle that says “feet planted like putting down roots” is a metaphor to pay attention to the stability under the feet. Ultimately for health and functionality the body needs to be free and nimble.