Chapter 41 is a continuation of what we read in chapter 40. We read the Lord’s words in Isaiah 40:28-31, “Hast thou not known? hast thou not heard, that the everlasting God, the LORD, the Creator of the ends of the earth, fainteth not, neither is weary? there is no searching of his understanding. He giveth power to the faint; and to them that have no might he increaseth strength. Even the youths shall faint and be weary, and the young men shall utterly fall. But they that wait upon the LORD shall renew their strength; they shall mount up with wings as eagles; they shall run, and not be weary; and they shall walk, and not faint.” The Lord is able to strengthen the weak according to His own will and sovereignty. The Lord goes on to say in Isaiah 41:1, “Keep silence before me, O islands; and let the people renew their strength: let them come near; then let them speak: let us come near together to judgment.” The Lord calls all the nations together. At first, He tells them to “keep silence” and to “renew their strength.” He wants them to renew their arguments against Him and His strength. He goes on to tell them that after they have renewed their strength to come to Him with their arguments.

The Lord then speaks of a ruler that He will use to free His people from captivity in Babylon. We read in verse 2, “Who raised up the righteous man from the east, called him to his foot, gave the nations before him, and made him rule over kings? he gave them as the dust to his sword, and as driven stubble to his bow.” Although his name is not mentioned here, the Lord is speaking of raising up Cyrus to deliver His people from their captivity. Cyrus was, of course, not a righteous man, but he would be doing the righteous will of God. So, the question was asked, “Who raised up the righteous man from the east?” It was God that did this. In His power and sovereignty, he raised this man to be a blessing to the Lord’s people. Verses 9-20 are words of encouragement and assurance to the nation of Israel. Verse 20 says, “That they may see, and know, and consider, and understand together, that the hand of the LORD hath done this, and the Holy One of Israel hath created it.” The Lord would manifest Himself to His people, and other nations, so that they might know that He is the One who blesses them.

Now let’s look at the verses in question. Isaiah 41:15-16, “Behold, I will make thee a new sharp threshing instrument having teeth: thou shalt thresh the mountains, and beat them small, and shalt make the hills as chaff. Thou shalt fan them, and the wind shall carry them away, and the whirlwind shall scatter them: and thou shalt rejoice in the LORD, and shalt glory in the Holy One of Israel.” The object of the illustration in these two verses is to show that God would give them power, and that they would be able to defeat all the difficulties in their way.

A thresher was used to separate the seeds from the stalks and husks of the wheat. It does so by beating the plant to make the seeds fall out. Or it could be done by using oxen to pull a cart filled with stones to press it down, and at the bottom with iron teeth, which being drawn over the sheaves, separated the grain from the husk. Then a fan was used to blow the lighter parts away, and the useful seed of the wheat plant would remain on the threshing floor. This was uses metaphorically of the Lord Jesus in Matthew 3:12 which says, “Whose fan is in his hand, and he will throughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire.”

Going back to Isaiah 41: 15-16, we see the Lord’s people would be empowered to defeat their enemies. The ‘mountains’ that are mentioned reference the kingdoms that would come against them. They were promised victory as long as their hearts were turned to God so that in their victories, they would “rejoice in the LORD, and shalt glory in the Holy One of Israel.” (334.4)