The earliest description of the use of opium as a recreational drug in China comes from Xu Boling, who wrote in 1483 that opium was 'mainly used to aid masculinity, strengthen sperm and regain vigor', and that it 'enhances the art of alchemists, sex and court ladies'. He described an expedition sent by the Chenghua Emperor in 1483 to procure opium for a price 'equal to that of gold' in Hainan, Fujian, Zhejiang, Sichuan and Shaanxi where it is close to Xiyu. A century later, Li Shizhen listed standard medical uses of opium in his renowned Compendium of Materia Medica (1578), but also wrote that 'lay people use it for the art of sex', in particular the ability to 'arrest seminal emission'. This association of opium with sex continued in China until the twentieth century. Opium smoking began as a privilege of the elite and remained a great luxury into the early 19th century, but by 1861, Wang Tao wrote that opium was used by rich peasants, and that even a small village without a rice store would have a shop where opium was sold.