This verse also has been taken in different ways by interpreters: some take the word iron, when repeated in a different case, "Will iron break iron?" but others think the subject wanting in the clause, and consider people to be understood, "Will the Jews break the iron, even the iron from the north, and not only the iron but the brass also, or, the the brass mixed with iron?" There is in reality no difference, but in words only. If we read, "Will the iron break the iron from the north?" the meaning will be, "Though there be great hardness in you, can it yet break that which is in the Assyrians? but ye are not equal to them: make your strength as great as you please, still the Chaldeans will be harder to break you; for if ye are iron, they are brass or steel, and so it will not be possible for you to sustain their violent attacks." As the meaning of the Prophet is sufficiently evident, I will not insist on words, though the rendering I most approve is this, "Will iron break the iron (the repetition is emphatical) from the north and the brass?" We here also see that the design of the holy man was, to divest the Jews of that false confidence in which they boasted: for how was it, that they were so refractory, except that they did not dread any misfortune? As then they were secure, predictions had but little weight with them. Hence the Prophet, in order to beat down this ferocity, says, that there would be greater hardness in the Chaldeans, for they would be like iron, yea, and steel also. [1] It follows --

Footnotes

1 - If we consider what is said to the Prophet in Jeremiah 1:18, and in the twentieth verse of this chapter (Jeremiah 15:20), we shall see the meaning of this verse: he was no doubt the iron and the brass: and the opinion of Blayney is probable, that the "enemy" in the previous verse (which is a poetical singular for the plural enemies) is the nominative case to the verb "break." God, having before refered to what he had done for the Prophet, now says, -- Can he break the iron, The iron from the north and the brass? God had made him an "iron pillar, and a wall of brass:" and he asks now, was it possible for his enemies to destroy him whom God had thus made. The hardest iron came from the north of Judea. The future tense is to be read here potentially. -- Ed.

The steel - "brass," i. e., bronze. By the "iron" is meant Jeremiah's intercession; but this cannot alter the divine purpose to send Judah into exile, which is firm as steel and brass. For "brass" see Exodus 25:3 note. The alloy of copper and zinc now called brass was entirely unknown to the ancients.

Shall iron break the northern iron and the steel? - Shall our weak forces be able to oppose and overcome the powers of the Chaldeans? נחשת nechasheth, which we here translate steel, property signifies brass or copper united with tin, which gives it much hardness, and enables it to bear a good edge.

Shall (n) iron break the northern iron and the steel?
(n) As for the people, though they seemed strong as iron, yet they would not be able to resist the hard iron of Babylon, but would be led captives.

Shall iron break the northern iron and the steel? Can iron break iron, especially that which comes from the north, which was harder than the common iron; or steel, the hardest of all? though the Jews were hard as iron, they could not prevail against and overcome Jeremiah, who was made an iron pillar and brasen walls against them, Jeremiah 1:18, and so these words are spoken for his comfort and encouragement: or they may respect the Jews and the Chaldeans; and the sense be, that the Jews, as mighty and as strong as they fancied themselves to be, and boasted that they were, they could not find themselves a match for the Chaldean army, which came out of the north; and may be said to be as hard as the northern iron, which came from the Chalybes, a people in the north, near Pontus, from whom steel has its name in the Latin tongue; and this sense agrees with what follows.

steel--rather, brass or copper, which mixed with "iron" (by the Chalybes near the Euxine Pontus, far north of Palestine), formed the hardest metal, like our steel. Can the Jews, hardy like common iron though they be, break the still hardier Chaldees of the north (Jeremiah 1:14), who resemble the Chalybian iron hardened with copper? Certainly not [CALVIN]. HENDERSON translates. "Can one break iron, (even) the northern iron, and brass," on the ground that English Version makes ordinary iron not so hard as brass. But it is not brass, but a particular mixture of iron and brass, which is represented as harder than common iron, which was probably then of inferior texture, owing to ignorance of modern modes of preparation.

The northern iron - As the northern iron and steel is the hardest, and no iron could break that, so God having edged and hardened their enemies, the Chaldeans, all opposition to them would signify nothing.