wilderness . . . desert. These are metaphors for alienation and anguish (14:17; 27:10; 64:10). God alone can transform the desert into a blooming and fruitful oasis, a figure for the fullness and joy of His salvation (32:15, 16; 35:1, 6; 41:18, 19; 43:19, 20; 48:21; 51:3).
prepare . . . make straight. “Prepare” means to “remove every obstruction” (57:14). God will remove all obstacles at His coming, but He expects His people to prepare for the kingdom (62:10) and requires the nations to assist the progress of His salvation.
way . . . a highway. See note 11:16. Here these are figures for human hearts that must be prepared through repentance (35:8–10; Luke 3:3–9). When that happens, God’s glory appears on earth.