The Origins of Medicine: Exploring the History of Drugs

Drug is as old as man himself, the first time when a person chewed, a herb to cure his diarrhea or elevate his mood, it signaled the beginning of pharmacology.
Basically dug is a chemical agent, interacting and binding at molecular levels and shapes the function of living systems right up to cellular level.
This word “drug” is derived from Dutch word drogue meaning herb.
"Drug is a chemical substance (other than food) which interacts with living cells and is used for the treatment, prevention, diagnosis and mitigation of disease".
Early in history a natural bond was formed between religion and use of drugs. Priests, Shamans, Witches and holy persons were mediators between this world and spiritual world. A concept then was prevalent that sickness is caused by demons, and that these had to be cast out in order to restore health.
In early periods religion dominated and divine intervention was called upon for cure of ailments. As the knowledge of drugs and chemicals advanced the divine intervention started to loose its importance and the treatment of disease was taken over by the priests rather than gods. Advancement in the knowledge of therapeutic value of natural products led to decrease in dependence on supernatural powers and various gods.
The priests gained experience by treating patients and the approach gradually became more scientific. This was the foundation of practice of medicine and use of drugs. Thus sequence of events started from magic to gods and priests experience and culminated in scientific knowledge based on reasons and logics.