Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
Deuteronomy Chapter 8
But by every word that proceedeth out of the mouth of the Lord - literally, "every outgoing of the mouth of the Lord." Compare Deu 29:5-6. The term "word" is inserted by the King James Version after the Septuagint, which is followed by Matthew and Luke (see the marginal references). On the means of subsistence available to the people during the wandering, see Num 20:1 note. The lesson was taught, that it is not nature which nourishes man, but God the Creator by and through nature: and generally that God is not tied to the particular channels ("bread only," i. e. the ordinary means of earthly sustenance) through which He is usually pleased to work.
They had clothes, it would seem, in abundance (compare Exo 12:34-35) at the beginning of the 40 years; and during those years they had many sheep and oxen, and so must have had much material for clothing always at command. No doubt also they carried on a traffic in these, as in other commodities, with the Moabites and the nomadic tribes of the desert. Such ordinary supplies must not be shut out of consideration, even if they were on occasions supplemented by extraordinary providences of God, as was undoubtedly the case with their food.
See Exo 3:8 note, and the contrast expressed in Deu 11:10-11, between Palestine and Egypt.
The physical characteristics and advantages of a country like Palestine must have been quite strange to Israel at the time Moses was speaking: compare Deu 3:25 note. To have praised the fertility and excellence of the promised land at an earlier period would have increased the murmurings and impatience of the people at being detained in the wilderness: whereas now it encouraged them to encounter with more cheerfulness the opposition that they would meet from the inhabitants of Canaan.
Vines - The abundance of wine in Syria and Palestine is dwelt upon in the Egyptian records of the campaigns of Thotmosis III. Only a little wine is produced in Egypt itself. The production of wine has in later times gradually ceased in Palestine (circa 1880's).
For brass read copper (Gen 4:22 note); and compare the description of mining operations in Job 28:1-11. Mining does not seem to have been extensively carried on by the Jews, though it certainly was by the Canaanite peoples displaced by them. Traces of iron and copper works have been discovered by modern travelers in Lebanon and many parts of the country; e. g., the district of Argob (see Deu 3:4 notes) contains iron-stone in abundance.
Render: "Who brought thee through that great and terrible wilderness, the fiery serpent and the scorpion, and the dry land where are no waters." On the fiery serpents see Num 21:6 note.
To do thee good at thy latter end - This is presented as the result of God's dealings.