In this section of the Kashf al-Mahjub, Hujwiri holds that the knowledge obligatory upon the servant concerns God and the gnosis of Him, and he divides it into two kinds: principles (usul) and derivatives (furu). Each kind has an outer (zahir) and an inner (batin) dimension. The outer of the principles is the verbal profession of the testimony of faith and its inner is the realization of gnosis; the outer of the derivatives is the practice of religious works and its inner is the purification of intention. Neither dimension can stand without the other: outer reality without its inner is hypocrisy, inner reality without its outer is heresy (zandaqa), outer law without its inner is mere self-will, and inner without outer is caprice. Hujwiri then states that the knowledge of reality (ilm-i haqiqat) rests on three pillars — knowledge of God's essence and unity with the negation of anthropomorphism, knowledge of His attributes and their rulings, and knowledge of His acts and wisdom — para...