What document did Abraham Lincoln feel was the foundation for our nation

The document that Abraham Lincoln felt as the foundation of America is the Declaration of Independence.

By issuing the declaration of Independence, adopted by the continental congress on July 4 1776, the 13 American colonies severed their political connections to great Britain. The declaration summarized the colonists' motivation for seeking independence.

By declaring themselves independent as a nation, the American colonists were able to confirm an official alliance with the French government and to obtain assistance from France in the war against Great Britain.