The final phrase of the introduction should contain the thesis statement. My lecturer advised me to utilize the following thesis statement: The blurred borders between reality and imagination generate a figure in Ambrose Bierce's "An Occurrence at Owl Creek Bridge" who appears to exist in his dream-like condition. This statement can be used to guide your analysis of the short story. You could say that Ambrose Bierce was trying to warn people about the dangers of pursuing the "blurred borders" between reality and imagination. Alternatively, you could argue that he was simply being ironic when he wrote this story. Either way, you can see that there is no single right or wrong answer to the question of what constitutes a good thesis statement. It depends on how you want to interpret the text and use it to support or refute some aspect of its theme.