On the other hand, there is the order from the Signifier to his signs, from the Artisan to his works. In this branch the seeker experiences divine attraction (jadhba), and is able to enter the order with a glimpse of its endpoint, of direct apprehension of the Divine Presence towards which all spiritual striving is directed. This does not replace the striving to purify the heart, as in the other branch; it simply stems from a different point of entry into the path. This is the way primarily of the masters of the Naqshbandi and Shadhili orders. Contemporary scholars may also recognize a third branch, attributed to the late Ottoman scholar Said Nursi and explicated in his vast Qur'an commentary called the Risale-i Nur. This approach entails strict adherence to the way of Muhammad, in the understanding that this wont, or sunnah, proposes a complete devotional spirituality adequate to those without access to a master of the Sufi way. Contributions to other domains of scholarship Sufism has contributed significantly to the elaboration of theoretical perspectives in many domains of intellectual endeavor. For instance, the doctrine of "subtle centers" or centers of subtle cognition (known as Lataif-e-sitta) addresses the matter of the awakening of spiritual intuition. In general, these subtle centers or latâ'if are thought of as faculties that are to be purified sequentially in order to bring the seeker's wayfaring to completion. A concise and useful summary of this system from a living exponent of this tradition has been published by Muhammad Emin Er. Sufi psychology has influenced many areas of thinking both within and outside of Islam, drawing primarily upon three concepts. Ja'far al-Sadiq (both an imam in the Shia tradition and a respected scholar and link in chains of Sufi transmission in all Islamic sects) held that human beings are dominated by a lower self called the nafs (self, ego, person), a faculty of spiritual intuition called the qalb (heart), and ruh (soul). These interact in various ways, producing the spiritual types of the tyrant (dominated by nafs), the person of faith and moderation (dominated by the spiritual heart), and the person lost in love for God (dominated by the ruh). Of note with regard to the spread of Sufi psychology in the West is Robert Frager, a Sufi teacher authorized in the Khalwati Jerrahi order. Frager was a trained psychologist, born in the United States, who converted