Why did he include the highlighted statemaent in his speech?

It's to know your purpose before you read something because a purpose can:

How did the older men calm the younger ones down when they learned from some of the prisoners where they were? (chapter 3 of the book night)

Have you ever thought you understood a person based on a story that you have heard about them? have you ever guessed about a person's personal life because of the clothes they wore? or, have you judged a person because of their friends? although classifying people in this way is typically discouraged, authors deliberately use your preconceived ideas to you form an opinion about the character or to at least have a better understanding. can you think of a time that you made a character call about someone based on external aspects? were you correct, or incorrect? has anyone ever made an incorrect assessment of you based on external aspects? write two paragraphs about it in your journal.