Why do speakers emphasize particular words and phrases?

To make the language more memorable
To remind the audience of the theme
To make a claim seem logical
To avoid counterarguments
What information would the viewer of the image have that the reader of Lincoln's Gettysburg Address might not have?

What the battlefield looked like
That many lives were lost in battle
That the Union soldiers were victorious
The serious nature of the battle
What word describes effective persuasion?

Claim
Comparison
Narration
Rhetoric