Distant reading methods allow us to identify and analyze shared passages (direct text reuse and paraphrase) across our premodern Arabic corpus, but also identify similarities and differences in topics and style, based on linguistic features of the texts, word frequencies, function words, rare words, and so on. Stylometry or computational stylistics deals with the latter. While text reuse and stylometry may work against each other, (unacknowledged borrowing affects topic-agnostic quantitative measures such as word frequencies), they can also be complimentary. Anonymous or unacknowledged authorship attribution, and genre detection are among the main applications in stylometry and we have already done some work in that direction for premodern Arabic stylometry. These applications and their potential will be explored through the case of the  Epistles of the Brethren of Purity (Rasail Ikhwan al-Ṣafāʾ) - a collection of 52 treatises plus two other "sister" –treatises (Risālat al-Jāmiʿa and Risālat Jāmiʿat al-Jāmiʿa) on a wide range of subjects, purportedly all known disciplines, by one or more anonymous authors supposedly in tenth-century Basra. The authorship, arrangement, and composition date of the Epistles are disputed and competing theories have been put forward. The widely varying manuscript tradition, attested only from about two centuries after the composition of the Epistles, suggests an open-text tradition since the beginning. Problematic modern editions have further complicated the matter and the potential of digital scholarship on the Epistles has yet to be realized. As the first application of stylometry to the Ikhwanian corpus, this paper aims to make a two-fold contribution: a contribution to these scholarly debates, by considering the stylistic features of the epistles, and towards the application of computational linguistics to a corpus of premodern texts in Arabic.