Heidegger's Bible Handbook: Isaiah: Arrangement of Material
6. An account of the order is difficult to elicit. The manner of the Prophets, consigning to writing a summary of the sermons delivered by them.
Now, since this book has distinct visions and sermons, published at diverse times, it is difficult to establish a general order, except according to those visions. The observation of Calvin, Præfatione in Esajam, will be helpful here, that it was customary for the prophets to consign to writing a summary of the sermons delivered by themselves, and to fix it for reading to the temple doors: and that it, when it had been displayed for a sufficient number of days, was removed by the Ministers of the Temple and deposited in the treasury, as a public monument. That the books of the Prophets were compiled in this way, he gathers out of Isaiah 8:1 and Habakkuk 2:2: yet not in regular order, but as opportunity served, were the sermons arranged, and from those the scroll composed.