This article studies the ideological identity of the authors of the Rasā’il Ikhwān al-Ṣafā’ and addresses the question of the authorship of the other works attributed to the Brethren of Purity. Based on these theosophical works, it provides new evidence for the authors’ political stance against the Abbasid state and confirms their Shii inclination and opposition to the Abbasid caliphs of their time. These findings highlight the Ikhwān’s involvement in political activities through preaching the end of the “state of evil” (...) and the beginning of the “state of good”. It also contributes to the debate on the Ikhwān’s relation to other political opposition movements against the Abbasid reign and their links to the Shii states. (shrink)