The Hebrew canonical order is not the same as that in your English Bibles. It has three parts: the Torah of Moses, the Prophets, and the Writings (aka Scriptures). The first section is the same five volumes as the English Bible with Genesis-Deuteronomy. The second section includes eight volumes: Joshua, Judges, Samuel, Kings, Isaiah, Jeremiah, Ezekiel, and the Book of the Twelve (the last are completely separate books in the English Bible -- aka the "minor" prophets). The Prophets follow the wisdom pattern of 3+1+3+1 (I now also might add that the former prophets (the first four, Joshua-Kings) follow an A,B,A',B' pattern...stay tuned for a future post on the book of Kings). The third section includes eleven volumes that I have argued before is a chiastic pattern opening and closing with Psalms and Chronicles and climaxing with Qoheleth (Ecclesiastes). Thus before I have shown the way the seams of the end of Deuteronomy (its 2nd epilogue) and Joshua 1 answer to the end of Malachi (its epilogue) and Psalm 1. What I would like to add to this observation is the contribution of the epilogue of Qoheleth (Ecclesiastes).
I have noted before the effect of putting Qoheleth at the climax of the writings is to end the editing of the Scriptures. This is because the epilogue to Qoheleth says, "Of making many books there is no end, and much study is a weariness of the flesh" (Eccl 12:12b). The practice of making books refers not only to the process of writing new books but also to the process of editing existing books. This verse has a particular purpose within the context of Qoheleth and that is a related purpose to what it adds in dialogue with the Hebrew canon. Part of the reason that nothing further need be said is that the main character of the book, Qoheleth, is a Solomonic persona; that is, he is a king and is able to investigate everything. As Enns puts it, "The king is more suited than anyone to make the claims Qoheleth makes. At his disposal are supreme wisdom, a supply of resources, and the luxury of time. No one else is so equipped to carry out so thorough and searching a critique of the human predicament" (Enns, Ecclesiastes, 133). Thus there is no need to say "anything beyond these" words (Eccl 12:12a). There is no need to add or subtract from the book and you do not need to try to replicate Qoheleth's quest since there is nothing new under the sun that you can add to it. This is also a fitting finish to the editing of the Hebrew Scriptures. There is no need to add to these words, no need to say anything beyond these words, nor to subtract from them, no need for further editing (the end of Revelation in the NT serves the same function for the NT canon).
The main places where we find editing in the Torah and Prophets is the additional epilogues given to both. As we have argued before more extensively, Deuteronomy has an additional poem and epilogue at the end of the book written from the perspective of a time well after the death of Moses when prophecy had ceased. Therefore, it is written from the same perspective of the epilogue to the Prophets when that collection arranged in the wisdom pattern of 3+1+3+1 was finished. These edits were done by wisdom sages, of which Qoheleth was one. The seams of the canon highlight the connection of wisdom and Torah. The very wisdom pattern structure of the Prophets points to the importance of wisdom. We have argued before (and also more extensively) that the reason for stressing wisdom is that the focus of the people during this period after the end of the Prophets and before the return of Elijah (i.e. the events surrounding John the Baptist) was the study of written Scripture (Torah, Prophets, Writings).
The epilogue to Malachi (the last part of the Book of the Twelve) says, "Remember the Torah of my servant Moses, the statutes and rules that I commanded him at Horeb for all Israel" (Mal 4:4 in English). The next book in the Hebrew Scriptures, opening the Writings, is Psalms and Psalm 1 (a wisdom psalm) says, "Blessed is the man...[whose] delight is in the Torah of YHWH and on His Torah he meditates day and night" (Psa 1:1-2). The extra poem and epilogue to Deuteronomy likewise had stressed the importance of Torah study (for example, see the expanded comments on the tribe of Levi who "shall teach Jacob your rules and Israel your Torah" (Deut 33:10)) and the theme of wisdom ("Joshua the son of Nun was full of the spirit of wisdom," Deut 34:9). One can and should argue that the ending of Deuteronomy is an argument for why one needs to study Torah. Like Qoheleth, the king, Moses is beyond compare (cf. Deut 34:10-12, the very end of the book). And then Joshua 1 (opening the Prophets) notes, "This Book of the Torah shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it..." (Psa 1:8). I have laid out the parallels between Deuteronomy and Malachi's epilogues and Joshua 1 and Psalm 1 elsewhere.
Now to finally get to the heart of the observation that we are adding here today. The frame narrator of Ecclesiastes in the epilogue, reflecting on the words of Qoheleth, says, "The end of the matter; all has been heard. Fear God and keep His commandments, for this is the whole duty of man [the whole duty of man is literally, "all the man"]. For God will bring every deed into judgment, with every secret thing, whether good or evil" (Eccl 12:13-14). These are the final two verses of Ecclesiastes/Qoheleth. Enns convincingly shows how "all the man" alludes to the same phrase in the words attributed to Qoheleth within the book. But for our purposes I want to note that this epilogue of the center of the Writings chiasm fits the theme of wisdom and Torah that we have noted above at the other seams of the Hebrew Scriptures.
Enns observes that the Hebrew word translated commandments here only appears this one time in the book but this is a clear reference to Torah keeping. He says, "For the frame narrator, to be a faithful Israelite likewise [i.e. like in other Second Temple works found outside the canonical Scriptures] links fear of God (wisdom) and keeping of the law (torah)" (Enns, Ecclesiastes, p.114). Furthermore, Enns says, "Fearing God and keeping the commandments represent two central Israelite themes: wisdom and law. And the call to trust God's ultimate justice in the affairs of humanity is a reiteration of these two themes" (p.152). And a third quote for good measure, Enns says, "These two principles [trust, fear God; and obey, keep the commandments] sum up the heart of both Israel's wisdom and legal traditions, for both covenant reverence and submission are components of wisdom and law" (p.186). I offer these quotes to show that the frame narrator of the book says the end of the matter is to fear God (wisdom) and keep His commandments (Torah). Thus at all of these seams of the Scriptures is this emphasis on wisdom and Torah.
I hope by now you are sufficiently convinced that the epilogue of Qoheleth deserves to be treated together with these other seams. And that the unifying theme of them all is to "fear God and keep His commandments" -- the intersection of wisdom and Torah.
This is what the Scriptures keep emphasizing for us to do -- the wisdom task of studying Torah and all of the written Scriptures. Qoheleth emphasizes that we should come back to this even when we are at our rope's end -- even when we are utterly frustrated because of the absurdity of life and utterly frustrated because our theology (Torah) says one thing but we see another and because our wisdom writings say one thing but we see another. The Prophets emphasize that we should come back to the wisdom task of studying the written Scriptures (especially Torah) because that was the way to know the will of God since prophets were no longer speaking until the events surrounding the return of Elijah. Meditate on it day and night -- study it with wisdom. Fear God and keep His commandments.