When fully stated, the evidence indicated under (2) and (3) above is of a convincing character, and the conclusion that Chronicles‒Ezra‒Nehemiah were at one time a single work should be unhesitatingly adopted. § 3. DATE AND AUTHORSHIP (1) _Date and Unity._ The scope of our inquiry in this section requires to be defined with some care. In dealing with any work which is chiefly a compilation of older material, it is necessary clearly to distinguish between the dates of the various sources which can be recognised or surmised and the dates of the writer or writers who have effected the compilation. When we examine the structure of Chronicles its composite nature is at once evident. Many long and important passages have been taken, with or without adaptation, directly from the existing books of Scripture. The date of all such passages, of course, falls to be considered in the commentaries on Samuel or Kings or wherever their original setting may be. The remainder of Chronicles presents an intricate but interesting problem. It has been held that there are no sources involved in this remaining portion but that the whole is the free composition of the writer who quoted or adapted the passages from earlier books of Scripture referred to above. According to the view taken in this volume, sources other than these “canonical” books were utilised in the formation of Chronicles, although for reasons suggested in § 5 (q.v., pp. xxxvi f.) such sources are not easy to distinguish from the work of the compiler himself. The little which can be said regarding the origin and history of these supposed sources may conveniently be reserved for the section dealing with the _Sources_ (§ 5). The question, therefore, which is before us in this section is the date of the editorial process to which we owe the present form of Chronicles. Fortunately the answer is simplified by one important fact, namely the remarkable homogeneity of Chronicles‒Ezra‒Nehemiah. To such a degree are these books characterised by unity of style, vocabulary, standpoint and purpose (see below; also § 2 and § 6), that we may safely conclude they are essentially the product of one mind: they have reached _substantially_ their present form in the course of a single editorial process. Conceivably the work was achieved by a small body of Levites (see below under _Authorship_), contemporaries, sharing the same training and outlook; but it is much more reasonable to infer the activity of a single writer――the _Chronicler_. It is his date which we proceed to consider. The evidence may be grouped under three heads, of which the last two (B, C) are of chief importance. (A) (1) In 1 Chronicles xxix. 7 a sum of money is reckoned in _darics_, a Persian coinage introduced by Darius I (521‒486 B.C.).