Answer:The phrase "four score and seven" is an allusion, or reference to another person or document. Here Lincoln is echoing the Bible's language for the life of a human. Psalm 90 gives the standard life as "threescore years and ten." Lincoln uses other allusions throughout his speech. He concludes his first sentence with a more explicit allusion to the Declaration of Independence by using the line "that all men are created equal." This is also an appeal to a shared value, the value of equality.
