The word drug probably comes from the Greek pharmacon, remedy. Among the ancient Greeks, the pharmacos was the sacrificial victim, the scapegoat: his killing made it possible to remove divine punishment from the population. The practice, in vogue among most of the ancient peoples, revealed its intrinsic ambiguity: with the certain death of a few, an attempt was made to guarantee the hoped-for salvation for many, thus giving both death and life at the same time.
In parallel, the pharmacon substance had to remove the evil spirit that afflicted it from the sick body and the victim, in this case, could also be the patient himself. The ambiguous nature of drugs was quite evident (ambiguity preserved in the Anglo-Saxon languages where the term drug can take on two clearly opposite meanings: drug and drug): depending on the dosage and, more generally, on the use made of them, they could be curative or toxic. Homer, moreover, uses the same term to indicate both the nepenthe – probably an opium-based drink that Helena offers to the disconsolate Telemachus in search of news of her father (Odyssey, book IV, vv. 219-234) – and the evil potion with which the sorceress Circe had transformed Ulysses' companions into pigs (op. cit., X, 210-243; probably an infusion of nightshade with depersonalizing effects).
Dulacamara (Solanum Dulcamara) – Solanaceae family
The ambiguity of medicines was so clear that the Greek world had, so to speak, institutionalized it in the myth of Asclepius (Aesculapius), the divinity who had learned a large part of the medical art from Chiron, but who had then acquired, thanks to Perseus, an infallible remedy for getting rid of enemies and reviving friends: with the liquid gushing from the side of Medusa's neck, she killed; with the one coming from the opposite side he gave life to his friends (it seems that he had taken to resurrecting so many dead as to empty Hades. Zeus, fearing that the order of the universe would be overturned, struck Asclepius with lightning). In Greek art Asclepius is always represented with one or two snakes which perhaps recall the origin and ambivalence of his powers.
Asclepius, Greek god of medicine 
Moreover, much earlier (about 1200 BC), in the Bible the serpent had taken on the ambiguous symbolic value of life and death, fertility and temptation. Apart from what happened in the earthly Paradise, in the book of Numbers (21, 8-9) one of the various moments of intolerance of the Jewish people in the desert is reported: they were tired of feeding on the usual manna. Then God punished them by having venomous snakes bite them.
