A mystical aspect of Islam that is particularly close to Iranian hearts, tassawof (mysticism) is ultimately discovered in and derived from the Quranic verses. According to Sufis, God must be felt as a light that shines in the believer's heart and the heart must be pure enough to receive the light. The two are separated: man's soul is in exile from the Creator and longs to return 'home' to lose himself again in Him. Sufism has various orders and throughout Iran you can find khanqas (prayer and meditation houses) where people go to worship. Sufism does not conflict with Shiism or Sunnism, yet is treated with suspicion by the authorities.
Some of Iran's greatest thinkers, poets and scholars have had Sufi mystic tendencies, including Sohrevardi, Ghazali, Rumi, Hafez and Saadi.