Shia Islam is a branch of Islam in which one finds some of the most esoteric interpretations on the nature of the Quran. Shia interpretations of the Quran concern mainly issues of authority where the concept of Imamat is paramount. In Twelver Shia Islam, there are mainly two theological schools: the Akhbari and the Ususli. The former school interprets the Quran mainly through reliance upon traditions (hadith) ascribed to the Imams. The latter school gives more power to independent reasoning and judgment (ijtihad). Ismaili interpretation shares common ground with Sufism. The method is called "kashf", an "unveiling" to the heart of the interpreter, and it is dependent upon the master, the grace of God, and the spiritual capacity of the interpreter.