The Vital Gate as the Motive Power of Qi
Although it is held that the area between the two kidneys is the vital gate, there is neither water nor fire within it, but rather the motive power of qi, and it is by no means a physical organ. Sun Yikui of Ming Dynasty held that the motive power of qi between the kidneys is a pivot of vitality. Although the motive power of qi is the foundation of the viscera, it can not be thought of as fire.
Though medical experts may differ in opinion regarding the vital gate, there is no dispute regarding its main physiological functions. The vital gate is the root of the primordial qi and is a resource of heat power of the human body. It warms all the internal organs and tissues, and promotes the functional activities of the viscera. Additionally, the vital gate plays a part in the reproductive and sexual functions of the human body. TCM has observed through clinical studies that the decline of vital gate fire can manifest in a decline of sexual and reproductive functions apart form those symptoms caused by a deficient kidney-yang. Most traditional herbs used in reinforcing the vital gate fire also function in replenishing kidney-yang. In short, the fire of the vital gate corresponds to kidney-yang.
