In 63 BC, in a stone fortress on the Crimean coast, the most-feared enemy of the Roman Republic raised a small gold goblet of mixed poisons to his lips and drank it. He had spent forty years immunising himself against every known poison. The poison did nothing. He had to ask his Celtic bodyguard to draw a sword and stab him. He was nearly seventy years old.

His name was Mithridates the Sixth, King of Pontus. He had inherited the kingdom at the age of eleven, on the southern coast of the Black Sea, in 120 BC. His father had been assassinated by poisoning, possibly by his mother. The boy-king fled into the wilderness, lived as a hunter, returned at seventeen, and seized the throne by force. He executed his mother. He executed his brother. He took the throne, and then he took the precaution that would define his life.

He decided he would never die the way his father had. Every day, at the royal table at Sinope, his court physician prepared for him a small dose of every poison known to the ancient Greek world. Hemlock. Aconite. Belladonna. Arsenic. Scorpion venom. Viper venom. The dose was deliberately small. He grew immune. Over the next forty years he built an empire from Pontus across the Black Sea, fought three wars against the Roman Republic, ordered the massacre of eighty thousand Roman colonists in one day in 88 BC, and was finally defeated by Pompey the Great in 66 BC. He retreated to his fortress at Panticapaeum in the Crimea. His own son Pharnaces rebelled against him. Trapped on the upper floor of his palace by his son's troops, Mithridates assembled the cup of mixed poisons he had spent his life preparing for this exact moment.

The poison did nothing. He had immunised himself too well. His Celtic bodyguard, Bituitus, finished the job with a sword. His body was sent to Pompey, who buried him in the Pontic royal tombs at Sinope. The Romans took Mithridates's personal recipe for the antidote, the Mithridatium. The physician Andromachus, court doctor to the Emperor Nero, refined it into a fifty-four-ingredient preparation. The Mithridatium remained the most-prescribed antidote in European pharmacy until the eighteenth century. The technique of self-immunisation by progressive small doses still bears his name. It is called mithridatism.

I do one of these a day. Dead serious. Subscribe.