The Book of Animals is the first comprehensive book written in Arabic on zoology. In it, its author, al-Jahiz, discusses the Arabs, their conditions, customs, beliefs, and sciences, as well as some issues of jurisprudence and religion, and a selection of Arabic poetry, proverbs, rhetoric, and theological criticism. All those who wrote before Al-Jahiz in this field, such as Al-Asma'i, Abu Ubaidah, Ibn Al-Kalbi, Ibn Al-A'rabi, and Al-Sijistani, dealt with one animal, and their interest was linguistic rather than scientific. However, Al-Jahiz was interested in language and poetry, in addition to researching the natures, instincts, conditions, and habits of animals. Al-Jahiz's Book of Animals is considered one of his largest books ever, and his circle of knowledge is broad in scope. The book is a prominent image of the multifaceted culture of the Abbasid era, as it contained natural knowledge and jurisprudential issues, and discussed the politics of nations. It also spoke about all religious sects, geographical issues, and the characteristics of countries, and the effect of the environment on animals, humans, and trees. It dealt with medicine and diseases of animals and humans, in addition to a number of medical terms, plants, animals, and minerals, and selected verses from rare Arabic poetry, popular proverbs, and funny anecdotes.