Marvels of the Heart is a classic Sufi manual on the 'science of the heart.' For Sufis, the heart is more than a physical organ, it is the seat of the soul, which holds the key to the intimate relationship that exists between the body and spirit. Each heart, according to traditional wisdom accumulated over centuries of spiritual practice, possesses four qualities: predatory, animal, demonic, and angelic. The latter represents one's true origin and potential, and through the proper use of the intellect and by engaging in spiritual practices, one can restore equilibrium to his inner core. As the Qur'an says: By the remembrance of God do hearts find peace.