The Ikhwan al-Safa (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 Rasa''il Ikhwan al-Safa (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 Rasa''il constitutes a paradigmatic legacy in the canonization of philosophy and the sciences in mediaeval Islamic civilization, as well as having shown a permeating influence in Western culture.The present volume is the first of this definitive series consisting of the very first critical edition of the Rasa'' il 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 mankind. Perhaps yet more relevant in modern times, the Ikhwan demonstrate the arrogance of man''s claim to superiority, in contrast to the animals'' pious understanding of their respective roles within nature. The fable complements and expands upon the short exposition on zoology featured at the beginning of the epistle.