Into expire lies inspire. The only question is how to work and treat expire, and adjourn this work on changings yet happened and preparing chagings happening.
Said in other terms you have the yin disclosure from a correct yang, at the end and as a part of a correct yang. To define and work on yang is the question now
* Ilse Middendorf worked very well to define what the yin was, looking for the definition of correct inspire. She took away totally the yang since she saw the prevalence of this into inspire and wanted to avoid the loss of the totally yin principle that is at the basis of inspire nature. Linklater has found back a yang but does start not from where has to, they are expire and inspire one into the other defined and separeted but not far. External muscles can make mixed actions, not the root.
** Manuel Garcia worked truly well on the expire pure and correct that has as a disclosure the opening of the throat that appears when diaphragm make an inspire without interrupting the sound. And the principle of Belcanto italian technique is to find the inspire from the expire. Correct expire is crucial, not being just a pushing of air.