 From Epistle 43 onwards, the Ikhwân build their own system from a religious point of view, often in the fragmentary style typical of Muslim esoteric writings. Epistle 43 considers the way towards God through purification; then the beliefs of the Ikhwân al-Safâ’ and of the so-called “Divines,” the heirs of a prophetic tradition whose origin is ascribed to the ancient wise men (Epistle 44). Epistle 45 expounds the organization of the Brotherhood based on mutual help. Epistle 46 considers the faith, not only of Islam, but also of the former monotheistic religions and of the ancient wise men. Epistle 47 considers prophecy and the imamate. Epistle 48 discusses propaganda. Epistle 49 deals with a key theme in the encyclopedia – the existence of disembodied agents in the world, based on the Ikhwân’s idea that the full truth of the Qur’ân, obscured in their time by ignorance and distortions, could only be restored thanks to the study of the rational sciences developed by the Greek philosophers. In the surviving manuscript tradition, Epistle 49 appears in two versions, a short and a long one. The short one clearly preserves an older text. The long one contains a detailed elaboration of part of the short one. The short version also consists of two parts; the second is a commentary on the Epistle by an author other than that of the first, namely Maslama al-Qurtubî al-Majrîṭî, during his stay at Basra in 936-7. At the same time, Maslama should have also composed what de Callataÿ identified as the “short version” of Epistle on Magic, to which Epistle 49 was to be an introduction. In fact, both treatises aim to prove the existence of spiritual beings: magic in all its forms consists precisely in the acts of such spiritual beings. The long version would have been composed by Maslama after his return to Cordoba. In the printed editions, the final part of the short version is added to the text of the long version, but the addition is not found in any of the MSS examined in the new edition, while it might be found in the MS on which the first printed edition was based (that of Bombay, 1887-1889); but we do not know if such MS still exists (Madelung et al. 2019, 1–3). Epistle 49 is a complex exposition of Ikhwanian cosmology, remarkably different and richer than that exposed in any other epistle. This exposition is merged with the authors’ religious vision on the relationship between God and the world (Uy in Madelung et al. 2019, 8). A new vision of the Ikhwân’s magic as the “conceptual and practical pivot” of their religious-political reform based on inclusion and tolerance is in Saif 2019; a study of the so-called “longer version” of Epistle 52 in Saif 2020. Epistle 50 discusses the various kinds of 'administration' (physical, spiritual, personal, familiar, etc.), the core of the Epistle being the religious and philosophical approach to God. In the new edition, the treatise appears purged of all the passages that led Corbin to his esoteric interpretation (Baffioni in Madelung et al. 2019, 148 ; Baffioni 2019d). Some MSS provide additions and/or versions radically different from those reported in the other consulted manuscripts and in the printed versions available (Baffioni in Madelung et al. 2019, Appendices A–D, 237–364; with regard to additions to other epistles see Baffioni 2019a, 2019c). Noteworthy is the addition in MS Esad Efendi 3638 that explains the story of Adam meant as the progenitor of huimankind, the first speaking prophet and the heavenly imâm (ed. and tr. by Baffioni in Madelung et al. 2019, 237–277; cf. also Baffioni 2020b). Apparently, Epistle 51 duly gathers up the threads of the whole (often repeating contexts of previous treatises), but its recent editor has also ascertained the existence of two versions of it, maybe even three (Alshaar in Madelung et al. 2019, 381ff.). Epistle 52 On magic is the last in the corpus, missing in some editions and considered by some scholars (Bausani 1978, 12 and 279) as spurious, and of little value, so the Risâla al-Jâmi‘a would be the true fifty-second one (cf. de Callataÿ 2011, 3). However, de Callataÿ inclines to the view that the ‘short version’ of this treatise, namely, the part approximately corresponding to the first thirty pages of the Beirut edition, is genuine (de Callataÿ 2011, 5ff).