The second aliyah gives some laws of a king of Israel. The Torah says that G-d will choose the king. Furthermore, this king shouldn't amass too many horses for himself, or wives, or gold and silver. The king must write for himself two scrolls of the Torah and keep one with him at all times and learn from it every day. In the sefer Derech Mitzvosecho, it says that this mitzvah of a king of Israel has the purpose of instilling in us the fear of G-d, and our subjugation to Him, and our acceptance of the Yoke of Heaven. This is because the king of Israel is himself nullified to G-d, therefore, when the Jewish nation subjugates itself to a king, they nullify themselves to G-d as well.