Although the author and date of composition of the Su-nu ching, or Classic of the Pure Maiden, an ancient manual of techniques of the boudoir, are unknown, a line in a poem by Chang Heng written during the Eastern Han (A.D.25 to 220) goes "The Pure Maiden is my teacher / Tien Lao instructed the Yellow Emperor," indicating that the book dates back to that period or earlier.
就以專門傳授「房中術」的素女經而言，雖然作者、年代均已不可考，但是東漢張衡在朱府中提及「素女為我師、天老教軒皇」，可見東漢或更早即已流傳，迄今已有千餘年歷史。