Around 800 AD, Chinese alchemists were hard at work on something ambitious: a potion for eternal life. 

Their experiments mixed saltpeter, sulfur, and charcoal, common ingredients in the era's medicinal toolkit. Instead of immortality, they got something else entirely. The mixture ignited. They had invented gunpowder.

What started as a failed elixir became one of the most consequential discoveries in history, eventually giving rise to fireworks, and centuries later, firearms and explosives. 

The alchemists were searching for a way to cheat death. They ended up creating something that could deliver it, and, in its more celebratory form, light up the sky instead.