very different from its conventional meaning. For example, Hamadani, in his book Tamheedat ('Preludes'), interprets Q104:6–7 ("It is a fierce fire created by God, to penetrate into the hearts."), which conventionally refers to the punishment in hell, to be the passion of divine love. Hamadani interprets Q14:48 ("On the Day when the earth is changed into another earth, and the heavens, and they will emerge before God"), which conventionally describes the Day of Judgment as a description of the moment of spiritual awakening or enlightenment. Sufis believe that Quran's initial letters (Muqatta'at) conceal mysteries that can not be fully expressed in words and should be understood as mystic experiences. In Sufi commentaries of the Quran, Sufism concepts are commonly related such as the hierarchical levels of realities in human experience (human, supra-sensible, and divine levels), the various states of consciousness such as sustaining in hell (khaledeen in gahanm) and residing in paradise (khaldeed in janna), and the ideas concerning the six subtleties (lataif-e-sitta). A hadith attributed to Muhammad is essential in understanding the inward aspects of the Quran, and it is fundamental to Quranic exegesis: "The Quran possesses an external appearance and a hidden depth, an exoteric meaning and an esoteric meaning. This esoteric meaning in turn conceals an esoteric meaning so it goes on for seven esoteric meanings (seven depths of hidden depth)." There is a statement made by the Imam, Jafar Sadiq (d. 765 CE): "The book of God comprises four things: the statement set down, the allusions, the hidden meanings relating to the supra-sensible world, and the exalted spiritual doctrines. The literal statement is for the ordinary believers. The allusions are the concern of the elite. The hidden meanings pertain to the friends of God. The exalted spiritual doctrines are the province of the prophets." Esoteric interpretations In Sufism The most important author of esoteric interpretation prior to the 11th century was Sulami (d. 1021 CE); without his work, most of the very early Sufi commentaries would not have been preserved. Sulami's major commentary was a book named haqaiq al-tafsir ("Truths of Exegesis"), a compilation of commentaries of earlier Sufis. Sahl Tustari (d. 896) was among the most important mystics in the early formative period of Islamic mysticism. His commentary (tafsir al-Quran al-azim) was compiled later by his disciples and preserved, as a commentary on the Quran. Tustari's commentary does not comprise interpretations of every single verse,