The Encyclopedia of the Brethren of Purity (Arabic: رسائل إخوان الصفا, Rasā'il Ikhwān al-ṣafā') also variously known as the Epistles of the Brethren of Sincerity, Epistles of the Brethren of Purity and Epistles of the Brethren of Purity and Loyal Friends is an Islamic encyclopedia in 52 treatises (rasā'il) written by the mysterious Brethren of Purity of Basra, Iraq sometime in the second half of the 10th century CE (or possibly later, in the 11th century). It had a great influence on later intellectual leading lights of the Muslim world, such as ibn Arabi, and was transmitted as far abroad within the Muslim world as al-Andalus.The identity and period of the authors of the Encyclopedia have not been conclusively established, though the work has been mostly linked with Isma'ilism. Idris Imad al-Din, a prominent 15th-century Isma'ili missionary in Yemen, credited the authorship of the encyclopedia to Muhammad al-Taqi, the 9th Isma'ili Imam, who lived in occultation in the era of the Abbasid Caliphate at the beginning of the Islamic Golden Age.Some suggest that besides Isma'ilism, the Brethren of Purity also contains elements of Sufism, Mu'tazilism, Nusayrism and others. Some scholars present the work as Sunni Sufi.The subject of the work is vast and ranges from mathematics, music, astronomy, and natural sciences, to ethics, politics, religion, and magic—all compiled for one, basic purpose, that learning is training for the soul and a preparation for its eventual life once freed from the body. Turn from the sleep of negligence and the slumber of ignorance, for the world is a house of delusion and tribulations. – Encyclopedia of the Brethren of Sincerity Source: Wikipedia (en)