This is a new English translation of a classic of medieval Islamic learning, which illuminates the intellectual debates of its age and speaks vividly to the concerns of our own. It is the most famous work of the Brethren of Purity, a tenth-century esoteric fraternity based in Basra and Baghdad. In this rich allegorical fable the exploited and oppressed animals pursue a case against humanity. They are granted the gift of speech and presented as subjects with views and interests of their own. Over the course of the hearing they rebuke and criticise human weakness, deny man's superiority, and make powerful demands for greater justice and respect for animals. This sophisticated moral allegory combines elements of satire with a thought-provoking thesis on animal welfare. Goodman and McGregory accompany their translation with an introduction and annotations that explore the rich historical and cultural context to the work.