What was the most important event that happened in Chapter 7 of Elijah of Buxton?

In Chapter Seven, Mr. Leroy stops working earlier than usual for lack of light from the moon. Elijah tries to talk to him about the incident at school on their walk home together. Going on with his story, and thinking Leroy is not listening, Elijah almost utters the word, "nigger," and Mr. Leroy slaps him down to the ground. He shows Elijah his slavery scars, including his missing little finger. He tries to make Elijah understand this is a word of hate, and is not to be carried to Canada. Elijah's father has warned him that former slaves are "toting things 'round with 'em that cain't be seen with your regular eyes." Elijah fully forgives Mr. Leroy for slapping him and learns his lesson.