Associate in your mind the “40’s” of Isaiah with the sovereign, great goodness of God. Though by the time of Isaiah’s writing this section Israel will have and will yet still suffer much, God promises them comfort. Chapters 40-55 declare that the enmity between God and His people will be over, through the forgiveness of Israel’s sins, when His wrath is satisfied (1).
How? First a voice will cry out to the people, to prepare their hearts - for the Lord Himself will come. (See Luke 3:4.) The voice will cry out that we are but a breathe (6-8; see 1 Peter 1:24-25). And yet the Lord will still come for us, not to judge but to reward (10; see Hebrews 11:6). He will be like a Good Shepherd to His people (11; see John 10:11), gathering them even when they/we stray (Luke 15:5).
Who could have thought up a God like this? Who could have crafted this plan for Him (13; see Romans 11:34)? No, this is all His doing, all from His gracious character, all done completely by His own free choice. Not that He needs any nation (15-17). He is God; He is great; He is good, to His people (18-26). So do not think O people of God, that your particular struggle is hidden from Him (27). You may be tired, but your Redeemer is not (28). Wait for Him (31); it’s your faintness that qualifies you for His strength (29-31).