An interpretative translation by Shaykh Tosun Bayrak of "Sirr al-Asrar" by Hadrat Abd al-Qadir al-Jilani (1077-1166AD), considered by many to be one of the greatest saints of Islam and the eponymous founder of the Qadiriyya order. This book, appearing in English for the first time, contains the very essence of Sufism, giving a Sufi explanation of how the outward practises of Islam--prayer, fasting, almsgiving and pilgrimage--contain a wealth of inner dimension which must be discovered and enjoyed if external actions are to be performed in a manner pleasing to God. When this is achieved the soul finds true peace and the spiritual life becomes complete.