Over the course of the eighteenth century, Enlightenment natural historians and classifiers redefined what it meant to be human. By 1800, they had recast the very idea of humankind, sorting the world’s peoples into rigid biological categories for the first time in history. Prize-winning biographer Andrew S. Curran retraces this often-misunderstood story by plunging into the lives and ideas of the most influential individuals behind this reconceptualization, among them Louis XIV, Voltaire, David Hume, Immanuel Kant, and Thomas Jefferson.

Moving from the gilded halls of Versailles to the slave plantations of the Caribbean, from the court of the Mughal Empire to the drawing rooms of Monticello, Biography of a Dangerous Idea not only reveals the Enlightenment’s entanglement with empire and oppression—it offers a bold reassessment of the era’s most celebrated luminaries.