Steel Wrapped in Cotton
When you are able to use your mind and not brute force, then where your mind goes, your chi follows. After a long period of practice and chi circulating freely every day, you develop Jing (an internal power which is different from hard force). This is what the Tai Chi Classics mean by “from true softness comes true hardness”. The arms of one who has Tai Chi kung fu will feel extremely heavy; like steel wrapped in cotton.