Sunni

In 1401, 69-year-old scholar Ibn Khaldun lowered himself down Damascus's walls in a basket to meet the conquering Tamerlane face-to-face---a living test of his revolutionary theories about how civilizations rise and fall. Writing in 1375, Ibn Khaldun invented sociology by identifying asabiyyah (social cohesion) as the fundamental force in history, describing how prosperity weakens the bonds that hold societies together in predictable cycles.

In 11th century Baghdad, the brilliant scholar al-Ghazl stood at the peak of intellectual achievement---and discovered that knowing about God wasn't the same as knowing God. His crisis, and the path he found through it, opened a way for the world to hold both rigorous reason and deep spirituality without choosing between them. In a time when we're still told we must pick sides---rational or faithful, scientific or spiritual---his life reminds us that these have never been opposites. They're partners. And we need both.