The Ikhwān al-Ṣafāʾ (Brethren of Purity), the anonymous adepts of a tenth-century esoteric fraternity based in Basra and Baghdad, hold an eminent position in the history of science and philosophy in Islam due to the wide reception and assimilation of their monumental encyclopaedia, the Rasāʾil Ikhwān al-Ṣafāʾ (Epistles of the Brethren of Purity). This compendium contains fifty-two epistles offering synoptic accounts of the classical sciences and philosophies of the age; divided into four classificatory parts, it treats themes in mathematics, logic, natural philosophy, psychology, metaphysics, and theology, in addition to didactic fables.

The present volume is the first of this definitive series consisting of the very first critical edition of the Rasāʾil Ikhwān al-Ṣafāʾ in its original Arabic, with a complete, fully annotated English translation. This epistle, The Case of the Animals versus Man Before the King of the Jinn (Epistle 22), prepared by Professors Lenn E. Goodman and Richard McGregor, is arguably the best known, on account of its prominent ecological fable, which casts the exploited and oppressed animals pursuing a case against humanity.