In his letter, Dr. Martin Luther King Jr. uses pathos effectively by appealing to the emotions of his audience to help them understand the purpose of protesting in Birmingham, Alabama. He acknowledges the suffering and oppression that African Americans faced in the city, highlighting the brutal treatment they received from police officers and the economic and social inequality they experienced. King also uses vivid imagery and metaphors to evoke a sense of injustice and urgency, such as comparing the protests to the biblical story of the Israelites in Egypt and likening the fight for civil rights to a fever that must be treated. By using emotional language and relatable examples, King is able to connect with his audience on a personal level and motivate them to take action against the injustices they face.