Zhòng Rén Zhī Xī Yǐ Hóu Zhēn Rén Zhī Xī Yǐ Zhŏng Zhŏng Yóu Gēn Yĕ
Everyone's breathing has to come through the Throat (Hou).
But a Perfected One's Breathing (Xi) comes from the Heels (Zhong).
For one Heel (Zhong) Follows (Zhong) after the other Heel.
Yòu Tāi Xī Jīng Yún Fán Rén Hū Xī Yŭ Zhēn Rén Hū Xī Yŏu Shū Fán-Rén
Likewise, the 'Fetal Breathing Classic' (Tai Xi Jing) says:
An Ordinary Mortal's (Fan Ren) breathing and a Perfected One's Exhaling (Hu)
and Inhaling (Xi) have certain oustanding differences.
[Nevertheless, they] and ordinary mortals
Xī Qì Chū Rù Yú Yān Hóu Zhēn Rén Xī Rén Xī Qì Yú Qì Hǎi
breathe Air (Qi) that comes in and goes out [only] through the Throat.
So both a Perfected One (Zhen Ren) and a Normal Human (Xi Ren) can breathe their Qi
so that it goes into the 'Upper Sea' (the 'Sea of Qi' in the Thoracic Cavity).
Shì Qì Zhī Gēn Bĕn Zhī Chŭ Yú Àn Wài Chū Yún Zhŏng Zú Wéi
Zhŏng Zhŏng Wéi Jiǎo Gēn Yĕ
It is correct that the Qi uses a fundamental base to dwell and operate from.
After one presses down it goes out.
To say 'it follows close to the Foot', is because the Heels follow close behind,
because the Heels are the Feet's Roots (Jiao Gen).
Cǐ Yán Zhŏng Zhŏng Wéi Qì Gēn Yĕ Gēn Zhī Yán
This says that the Heels are the Qi Root (Qi Gen) and the Heel is