Euclid is celebrated as the father of geometry, and author of the Elements, a book once revered like the Bible, but now a school text. Strangely, Greek manuscripts do not mention Euclid, but speak anonymously of the “author of the Elements”. Did Euclid exist? Was the real author of the Elements a woman, Hypatia? Was she black? The mystery geometry of black Egypt aimed to arouse the soul, and prove equity, as in Plato's story of Socrates and the slave boy. Early Christians had similar beliefs about the soul, but the church changed Christian doctrine to enable its priests to rule. When pagans resisted, the church retaliated violently: it smashed their temples, burnt their libraries, cursed the early beliefs about the soul, and banned philosophy. This plunged Christendom into its Dark Age, but catalysed the Islamic Golden Age. The contrast fuelled envy, and Christian priests incited the Crusades, hoping to grab Muslim wealth—but the Crusades failed beyond Spain. To convert Muslims, who accepted reason, the church now sought mathematics, connecting it to Christian doctrine by changing both. That led to a subtle religious bias in mathematics, and to its racist history. This book is for the layperson concerned that both biases are still being thrust upon schoolchildren today.