Answer:
Lincoln harkens back to the Declaration of Independence. The founding fathers conceived: had the idea;
all men are created equal, entitled to Life, Liberty, and Pursuit of Happiness.
Slavery flew in the face of that concept/idea. Lincoln was reinforcing it was time to end the slavery vs. freedom for all mankind addressed in the Declaration of Independence. The bloody civil war must end with return to a United States, offering freedom/rights to all.
Step-by-step explanation:
Gettysburg Address:
Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal. Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure.