the priest is smiling, and pleased that the child is so carefree. i think that he offers the sweets to try and befriend the person, and make his own life enjoyable. but the two must part and the priest looks over his shoulder, longing to be more like him. maybe the wise one is learning more from the child about his own loss of pleasure. perhaps regret. then maybe the monk has a child and misses it. or another regret, that he did not have children of his own. perhaps he is considering following along and learning to enjoy life more.