The writer wrote chapters 12-15 very skillfully to parallel chapters 8-11. Each section begins with Samuel warning the people about the dangers of their requesting a king (chs. 8 and 12). Each one also follows with a description of Saul's exploits (chs. 9-10 and 13-14) and ends with Saul leading Israel in battle (chs. 11 and 15). This parallel structure vividly sets off the contrast between Saul's early success as Israel's king and his subsequent failure. The reason he failed is the primary theological lesson of these chapters, and it is a continuation of the fertility motif.
Chapter 12 is another most important theological passage in Samuel along with 1 Samuel 7 and 2 Samuel 7. Here Samuel explained Israel's future relationship with Yahweh and the Mosaic Law since the people insisted on having a king and had rejected Yahweh and Samuel.
"With this address Samuel laid down his office as judge, but without therefore ceasing as prophet to represent the people before God, and to maintain the rights of God in relation to the king."127
"This chapter . . . formally marks the end of the period of the judges . . ."128