Adam Mizner - Huang Sheng Shyan lineage
Tai Chi push-hands, in Chinese tuishou 推手, consists of circular movements performed by two players. It involves martial arts techniques derived from the various forms, but Tai Chi is an internal martial art, which means that the techniques relies on internal energy, chi or qi 氣, not solely strength of the muscles. The principles for developing and using the chi is described in the Tai Chi Classics.
Some important texts were written by members of the Chen, Yang, and Wu (武) families, but the oldest classics are the ones from the Li family who trained martial art in the Thousand Year Monastery together with their cousin Chen Wangting.
You can read much more about the original classics in 'Tai Chi - The True History and Principles'.
"Move the qi like a nine swirled pearl (spiral)- let there be no part it does not reach.
Move the energy like folding steel a hundred times, such steel is tough and will not break....