According to Lincoln, why was the sacrifice made by the soldiers at Gettysburg worth the price they paid?

powers  are  denied  to the  national governmentin three distinct ways: some  powers, such as the  power  to levy duties on exports or prohibit the freedom of religion, speech, press, or assembly, are expressly  denied  to the  national government  in the  constitution.

it foreshadows the theme of the paragraph and hints the topic that will be discussed in the paragraph!