Well one thing that Abraham Lincoln embodied was unity. In his speech "A House Divided" it was all about being united, and if we were split up as a nation, or even within our own families we wouldn't be able to stand. The nation (or family) would fall apart because unless we are working together, things can't go correctly.
If you read through the other poems and memoir chapter, I'm sure you can come up with a few more answers.
