Abū Ḥāmid al-Ghazālī

The most celebrated scholar in the Islamic world at thirty-three, holding the premier chair in Baghdad — and at thirty-eight he could not speak. His tongue seized in the lecture hall. He gave away his position, left his family provided for, and spent eleven years wandering as an unknown, then came back and wrote the book that reconciled Sufism with orthodox law for good.

He makes the inner path respectable, which is why there is a fence to trade across a century later. Compare Maimonides, whose son then walked through the gate Ghazālī had opened — and note that both men wrote philosophy in Arabic for readers who had read each other.