A reference like this is called an allusion. Why do you think Abraham Lincoln alludes to a founding document in his speech?

Abraham Lincoln alludes to a founding document in his speech, such as the Declaration of Independence, to emphasize the values of equality, liberty, and justice that are enshrined in that document. By alluding to a founding document, Lincoln appeals to the shared beliefs and principles of the American people, and underscores the importance of upholding these values in the face of challenges and conflicts. Additionally, referencing a respected document like the Declaration of Independence lends credibility and authority to his arguments, and helps to inspire and unite his audience around a common cause.