Rabbi Gideon Weitzman, the rabbi of my shul/beit knesset in Modi’in, recently published an excellent book entitled, His Words, Their Voices: Essays on the Haftarot.
In his essay on the specific Haftarah (a section of the book of Prophets) that is read communally on the second day of Rosh HaShana, Rabbi Weitzman struck a chord with me by writing about the “playful child.”