The collection and arrangement of "The Twelve" are matters of obscurity, from which, however, three or four facts emerge that are tolerably certain. The inseparableness of the books is a proof of the ancient date of their union. They must have been put together before they were received into the Canon. The Canon of the Prophets--Joshua to Second Kings and Isaiah to Malachi--was closed by 200 B.C. at the latest, and perhaps as early as 250; but if we have (as seems probable) portions of "The Twelve,"[10] which must be assigned to a little later than 300, this may be held to prove that the whole collection cannot have long preceded the fixing of the Canon of the Prophets. On the other hand, the fact that these latest pieces have not been placed under a title of their own, but are attached to the Book of Zechariah, is pretty sufficient evidence that they were added after the collection and fixture of twelve books--a round number which there would be every disposition not to disturb. That would give us for the date of the first edition (so to speak) of our Twelve some year before 300; and for the date of the second edition some year towards 250. This is a question, however, which may be reserved for final decision after we have examined the date of the separate books, and especially of Joel and the second half of Zechariah. That there was a previous collection, as early as the Exile, of the books written before then, may be regarded as more than probable. But we have no means of fixing its exact limits. Why the Twelve were all ultimately put together is reasonably suggested by Jewish writers. They are small, and, as separate rolls, might have been lost.[11] It is possible that the desire of the round number twelve is responsible for the admission of Jonah, a book very different in form from all the others; just as we have hinted that the fact of there being already twelve may account for the attachment of the late fragments to the Book of Zechariah. But all this is only to guess, where we have no means of certain knowledge. "The Book of the Twelve" has not always held the place which it now occupies in the Hebrew Canon, at the end of the Prophets. The rabbis taught that Hosea, but for the comparative smallness of his prophecy, should have stood first of all the writing prophets, of whom they regarded him as the oldest.[12] And doubtless it was for the same chronological reasons, that early Christian catalogues of the Scriptures, and various editions of the Septuagint, placed the whole of "The Twelve" in front of Isaiah.[13]