How do you write essay with antonyms?

If synonyms are Words that have a similar or identical meaning ("big" and "large" mean about the same thing; "thin" and "skinny" mean about the same thing), then antonyms are Words that mean the opposite. For example, the opposite of happy is sad; the opposite of fat is thin. Without even realizing it, you probably use antonyms on a regular basis. To use them in writing, you might compare two things: my essay will be about good versus evil in Shakespeare's play "Macbeth."