 Part II of the Book of Letters gives an account of the development of the “syllogistic arts” (arts of reasoning such as rhetoric, dialectic and sophistic), culminating in demonstrative science, within a given linguistic and religious community, and their transmission from one community to another. Fârâbî is especially interested in the language of these arts, especially of demonstrative science. He talks about the origin of language as such; but language as it naturally arises is not well suited to being the vehicle of demonstrative science, because it is chiefly devoted to naming and describing the objects of immediate practical interest to human beings, which are not the main objects of theoretical interest. But natural language can be extended in two main ways to provide the terminology of the syllogistic arts. First, terms of ordinary language can be extended metaphorically to new meanings, and can then be frozen for use as technical terms; and this process of metaphorical extension and freezing can be repeated indefinitely many times. Second, new terms can be formed from old ones by regular grammatical processes of morphological derivation, and this type of extension too can be repeated and combined with the first type. Special problems, however, arise when the arts, especially demonstrative science, are transmitted from one community to another, and the translators must create a new technical vocabulary in the target-language. If the technical terms of the source-text were derived by freezing metaphorically extended words in the source-language, the translator may try to create new technical terms either by imitating the metaphors of the source-language in the target-language, where they may be much less natural, or else by forming new terms from metaphors more natural to the target language: either way, there is a risk of misunderstanding. Fârâbî talks about these problems in general, but he devotes special attention to the transmission of demonstrative philosophy and its vocabulary from Greek into (Syriac and thus) Arabic.