Isaac the Blind (Sagi Nahor)

"Father of the Kabbalah": the blind master of Provence — called Sagi Nahor, "abundant of light," the tradition's tenderest euphemism — first to speak systematically of Ein Sof and of the sephirot as contemplative stations. He famously protested when his Gerona students began writing the secrets down: "a book cannot be hidden in a cupboard" — the first recorded objection to exactly what this app does.