In spite of the apparent lack of unity indicated by the title, the subject of Book IX may be fairly described as mankind. It is true that language is the first topic, but it is brought in merely because Isidore believed that differences of race were based on differences of language. It is followed by a survey of the races of mankind, ending with an account of the races that had won military prominence. Isidore then turns to man within the state and treats of him first as a soldier and then as a citizen. Finally man is taken up as a member of the family, and an account of family relationship and of marriage is given.[321] [321] Isidore gives a table of “the prohibited degrees” within which marriage was forbidden by the rule of the church. Since the introduction of Christianity these had been steadily extended until in Isidore’s lifetime intermarriage within the seventh degree was prohibited by Pope Gregory. The analogy between the wide extension of “the prohibited degrees” in the dark ages and that found among primitive peoples generally is remarkable. Westermarck, _History of Human Marriage_, p. 297, says: “As a rule among primitive peoples unaffected by modern civilization, the prohibited degrees are more numerous than in advanced communities, the prohibitions in many cases referring even to all the members of a tribe or clan.” For an account of this development of marriage, see Westermarck, _op. cit._, p. 308, and Smith and Cheetham’s _Christian Antiquities_, art. “Prohibited Degrees.” This social phenomenon of the dark ages is a development parallel to the recrudescence of the primitive in the intellectual sphere which is illustrated in so marked a manner in the _Etymologies_ (_cf._ pp. 50–54). ANALYSIS I. Languages (ch. 1). II. Mankind (ch. 2). 1. Mankind the descendants of the sons of Noah (Secs. 2–37). 2. General view of the peoples of the earth with their Hebrew origin where known (Secs. 37–135). III. Empires, rulers, and warfare (ch. 3). IV. Terms relating to civil life (ch. 4). V. The family (chs. 5–7). 1. The direct line (ch. 5). 2. Relatives and degrees of relationship, with the “prohibited degrees” (ch. 6). 3. Marriage (ch. 7). EXTRACTS Chapter 1. On the languages of the nations. 1. The diversity of languages arose after the flood, at the building of the tower; for before that proud undertaking divided human society among different languages (_in diversos signorum sonos_) there was one tongue for all peoples, which is called Hebrew. This the patriarchs and prophets used, not only in their conversation, but in the sacred writings as well. At first there were as many languages as peoples, then more peoples than languages, because many peoples sprang from one language.