It is said that with drugs your first high is the best and never able to be duplicated. What keeps people using drugs, despite the downfalls associated with use, is that eternal quest for that ethereal feeling that they experienced the very first time. Pleasurable activities, like exercising, sex, laughter, touch, etc. can all become dangerously addictive. Exercise, sex, laughter, and touch all produce positive effects within the body via chemicals in the brain. These chemicals are called endorphins, a mixture of the two words endogenous, meaning from within the body, and morphine, a powerful pain fighting drug that is also used and abused for recreational purposes.
Endorphins are the body's internal pain regulators.
The drug opium has been used recreationally as early in the ancient Greek, Roman, and Egyptian cultures. British physician, Thomas Syndenham brought opium to the public to be used for medicinal purposes around sixteen-eighty. By the end of the seventeen-twenties opium was outlawed in China, due to it's high level of recreational use and abuse. This led to the Opium Wars between the China and England. Credit for the discovery and abilities of endorphins are given to various different people, at different times in history.