“I will go before you and level the mountains; I will break down the gates of bronze and cut through the bars of iron.
2. and 3. I will go before thee. These two verses contain nothing new; but, in general, he shews that Cyrus will gain an easy and rapid victory, because he will have the Lord for the leader of his expedition. Accordingly he promises that all crooked paths shall be made straight, because God will remove every obstruction.
Cyrus was a Mede, descended (as some say) from Astyages king of Media. The pagan writers are not agreed in their accounts of his origin. Some tell us that in his infancy he was an outcast, left exposed, and was saved from perishing by a herdsman's wife.
Commenting on Isaiah 45:1-4
I will go before thee, and make the crooked places straight,.... Or, "level the hilly places" (c); as pioneers do. The sense is, that he would remove all impediments and obstructions out of his way, and cause him to surmount all difficulties: I will break in pieces the gates of brass, and cut in sunder the bars of iron; with which the brasen gates were...