Avicenna
If you’re looking for a thinker who proved that reason and belief can actually work together, look no further than Avicenna (also known as Ibn Sīnā). Born in 980 in what is now Uzbekistan, he was a true polymath of the Islamic Golden Age — philosopher, physician, scientist, and poet. By the time he was 18, he’d already mastered medicine and was treating patients. But his influence didn’t stop there. He tackled big metaphysical questions, reworked Aristotle’s ideas, and laid the foundation for centuries of thought in both the Islamic world and medieval Europe. Avicenna believed in the power of reason to understand not only the natural world, but also the soul, ethics, and existence itself.