Tyson notes how lead does not naturally occur at Earth's surface but has been readily mined by humans (including the Roman Empire), and that lead is poisonous to humans.
Tyson merincikan bahwa timbal tidak terbentuk secara alamiah di permukaan Bumi, melainkan sudah ditambang oleh manusia (termasuk pada masa Kekaisaran Romawi), timbal beracun bagi manusia.