The third and final subdivision of this last part of the book (chs. 56-66) returns to many of the themes in the first subdivision (chs. 56-59). However, the structure of this subdivision is the mirror opposite of that one.
"Whereas chs. 56-59 begin with a discussion of the foreign converts (56:1-8) and end with a description of the Divine Warrior who battles alone for his people (59:15b-21), this final subdivision (63:1-6) begins with the description of the Divine Warrior (using some of the same language as a previous one), and ends with a treatment of foreign converts (66:18-24). But beyond that, in each case the central section deals with the inability of the people to produce the ethical righteousness called for (56:8-59:15a; 63:7-66:17)."700
In chapters 56-59 the major emphasis was on human inability to produce the righteousness that God requires, and the minor emphasis was on God's power to enable humans to live righteously. In chapters 63-66 the opposite pattern of emphases exists. Both sections, of course, flank chapters 60-62 with its emphasis on future eschatological glory.