Why a snake means both death and healing

A snake does something before your eyes that nothing else around you does. It crawls out of its old skin and leaves it behind whole - an empty translucent casing, imprinted with scales and eyes. There is the animal, alive, while its former casing lies apart like a discarded body. It reads exactly like this: it died and came back new.

The second observation is about place. A snake vanishes into a burrow, a crack, under a stone: it goes down into the ground, to the same place the dead go, and returns from there alive. For the Greeks, the underground and the dead belonged to one realm, and the snake moved through it in both directions - something people cannot do.

The third observation is harsher. A bite kills quickly, but a small amount of the same substance does not - much of old pharmacy rested on this, when medicines were made from poisonous substances. Ancient Greek had one word for it: pharmakon - poison, medicine, and remedy all at once. "Toxic" comes from the same source: toxikon meant "of the bow," from toxon, "bow" - the word for poison used to coat arrows.

The healing snake is not a metaphor but a specific cult. At sanctuaries of Asclepius, the best-known of them at Epidaurus, sick people spent the night in a special hall, waiting for a dream they believed could heal them. Nonvenomous rat snakes kept at the temple slithered freely across the floor: a snake's touch was read as a sign that the god had come. The staff with one snake coiled around it comes directly from there.

Then the symbol multiplied, and now three different snakes are confused with one another.

Now for venom. The ancient intuition that poison and medicine are related turned out to be literally true, though there was no way to test it then. Antivenom is made from the venom itself: small doses are injected into an animal, and antibodies are taken from its blood. And in the 1970s, peptides from the venom of the Brazilian jararaca snake led to the substance that launched a whole class of blood pressure drugs. What drops blood pressure to a deadly level, with precise calculation drops it to normal.