Spiritual cleansing

Rabbi Akiva returns home after years of learning and is about to knock on the door. Then he overhears his wife, and he turns his students around and leaves. Why would he do that, when a simple hello would have cost so little? The scene fits a puzzle in Parshas Matos. After the war with Midyan, Elazar gives the laws for purifying utensils and the Torah calls them "chukas haTorah" and not "chukas hakeilim." The Chofetz Chaim finds a message about fire, and about what consistency does to us.