Diversity of Leadership in American Society The best speeches demonstrate the power of a single voice. They may be delivered by politicians, preachers, or athletes. Some such as Abraham Lincoln’s Gettysburg Address or Martian Luther King Jr.’s “I have a Dream” speech, may inspire and encourage us, unite and guide us. Others, such as farewell addresses of presidents George Washington and Dwight D. Eisenhower, may warn or even alarm us. Whether they contain the polished prose and delivery of President John F. Kennedy’s inaugural address or the broken English of Bartholomew Vanzetti, great speeches remind us of the power of language and the diversity of leadership skills.