One or two considerations derived from the present arrangement will serve to throw light upon this point. In the first place, Book IV., as we have it, is evidently composite. Between Chaps. II. and III. there is a deep hiatus. In the former chapter the discussion of the Nile is cut short, and the author’s own view is not even indicated, much less established; while the latter opens so abruptly as at least to suggest that it may have originally been preceded by something with which it stood in organic sequence. Again, the several Books do not conform to the author’s division of the subject as set forth in the opening of Book II. (51), but follow--or precede--one another anyhow. Then, three of the Books (I. III. IV.) have a formal Preface, while the others have not, though in them, too, with the exception of the Sixth, the opening chapter is introductory in character. Any attempt to restore a more intelligible order must depend for its success on the extent to which we may assume Seneca to have been a methodiser. In Book II. i, he certainly states very distinctly the divisions of his subject--(_a_) things in the heavens, (_b_) things between heaven and earth, (_c_) things on the earth. But it by no means follows that he himself maintained this order of treatment, or that he always exhausted one subject before passing on to the next. The division evidently enumerates the subjects in order of dignity or worth, and may have little, if any, relation to the order of their discussion; in fact, in Book II. he goes on immediately to deal with meteorology, his second and not his first topic. Bernhardt (_Die Anschauung des Seneca vom Universum_, p. 7) frankly accepts the traditional order of the Books, and finds its explanation in the distinction between phenomena and elements. The first three Books deal with the phenomena of heaven, air, earth, respectively; the last four respectively with the elements--water, air, earth, fire. This is ingenious, if not altogether convincing.