The Agron was Saadia Gaon's first production, completed in his twentieth year (913). It is a double Hebrew language dictionary, the two parts being arranged according to the alphabetic order of initials and of final letters respectively. It was intended to be used in versification, in which acrostics and rhyme were the chief requisites. In a later edition, Saadia added the Arabic translation of each word, and also included passages concerning various "memorable subjects of the poets," and named the work in its new form "Kitab al-Shi'r." The Arabic introduction to the second edition and the Hebrew preface of the first have been in great part preserved (see Harkavy, "Studien," v. 39-59).