The connection between the Epistle of the Brethren of Purity and Isma'ilism might have suggested the adoption of this work as one of the main sources of what would become known as “Jewish Ismailism” as was found in late medieval Yemenite Judaism. This “Jewish Ismailism” consisted of adapting Ismaili doctrines about cosmology, prophecy and hermeneutics. There are many examples of the Brethren of Purity influencing Yemenite Jewish philosophers and authors in the period 1150-1550.[1][2][3][4]