Before revision: File:性命圭旨 反照圖 .png| "Illustration of Reverse Illumination", showing spinal acupuncture points associated with , 1615 The Ming c. 1500 (, Wondrous Discourse of Sunü) presents a new theory with a parabolic curve of sexual vitality, peaking at middle age, which separates the concept of sexual energy from simple ejaculatory potency (Wile 1992: 48).
After revision: "Illustration of Reverse Illumination", showing spinal acupuncture points associated with , 1615 The Ming c. 1500 (, Wondrous Discourse of Sunü) presents a new theory with a parabolic curve of sexual vitality, peaking at middle age, which separates the concept of sexual energy from simple ejaculatory potency (Wile 1992: 48).