2. The author of the book, whether it was Eleazar, Joshua, or Ezra?
Who the author of this book might be is not quite certain. That the book was gathered from an ancient historical register, which was called סֵפֶר הַיָּשָׁר, the Book of the Just, Joshua 10:13, Theodoret and others think. Others assert that it was written by Eleazar.[1] It is believed by the Hebrews that it was written by Joshua himself. And certainly, that Joshua’s last speech, and the words of the renewed covenant, which are described in Joshua 24, were consigned to writing by Joshua, the passage in Joshua 24:26, where he is said to have written in the book of the law of God those words, namely, his last words and the words of the covenant, the formulas of the stipulation of God and the promise of the people, does not allow of doubt. But even if all the remaining things were not able to be transcribed by Joshua διαρρήδην/expressly, since among those not a few things that happened after Joshua are comprehended, as it is gathered out of Joshua 4:9; out of Joshua 15:13-19 compared with Judges 1:10-15; and also out of Joshua 15; out of Joshua 16:10 compared with Judges 1:29; and finally out of Joshua 19:47 compared with Judges 18; and also out of other passages: nevertheless it is not unlikely that a great many things were committed to trustworthy records by Joshua, setting them down in a certain dairy, and also describing the principal things at greater length (especially since he lived for a sufficiently lengthy time in quiet after the wars), and in the progress of time were augmented, embellished, and reduced to order, with certain things that happened after the death of Joshua inserted, by a Prophet or θεοπνεύστῳ/inspired man, which sort Ezra was able to be.
[1] Aaron’s son, and contemporary of Joshua. See Exodus 6:23.