15. This can only partially apply to the spiritual revival in Hezekiah's time; its full accomplishment belongs to the Christian dispensation, first at Pentecost (Joe 2:28; Ac 2:17), perfectly in coming times (Ps 104:30; Eze 36:26; 39:29; Zec 12:10), when the Spirit shall be poured on Israel, and through it on the Gentiles (Mic 5:7).
      wilderness . . . fruitful field . . . forest--when Judea, so long waste, shall be populous and fruitful, and the land of the enemies of God shall be desolate. Or, "the field, now fruitful, shall be but as a barren forest in comparison with what it shall be then" (Isa 29:17). The barren shall become fruitful by regeneration; those already regenerate shall bring forth fruits in such abundance that their former life shall seem but as a wilderness where no fruits were.

JFB.