This volume presents three of the Epistles of the Brethren of Purity, a monumental work of medieval Islamic learning. Epistle 49 explores the hierarchy of existence; Epistle 50 describes the proper attitudes towards body and soul; Epistle 51 considers the arrangement of the world on numerical principles.

This volume presents three of the Epistles of the Brethren of Purity, a monumental work of medieval Islamic learning. These epistles explore applications of mathematics in music, medicine, and alchemy; scientific knowledge and the classification of sciences; and the place of the arts, industries, and trades in the Islamic cosmos.