The great speeches of antiquity include Socrates' Apology, Jesus' Sermon on the Mount, and Cicero's first speech against Catiline. Recent history is shadowed by Martin Luther King, Jr.'s "I Have a Dream" speech, Abraham Lincoln's Gettysburg Address, and the speeches of Winston Churchill, during the summer of 1940.
Patrick Henry delivered his "Liberty or Death" speech to a convention split between independence and colonial servitude; and, he convinced them that the only path for America was independence. Fictional speeches, particularly those in drama, have just as much power to move the masses. William Shakespeare's "Saint Crispin's Day" speech from his play "Henry V" is considered one of the finest ever delivered.
These great speeches delivered by great orators inspire and persuade the public at large. In the midst of a dark, seemingly hopeless situation, they can instill hope and unity among their audiences, as was the case with Lincoln's Second Inaugural Address and Churchill's "Their Finest Hour" speech.