Reread lines 13 21 what is lincoln's purpose in this paragraph and how does he achieve it

Lincoln's purpose in paragraph two was to open up a way for the South to join the Union again after the war was over. By saying that a majority of voters needed to approve of it, it would allow them admittance back into the United States, but of course this was not achieved until after his death. 

The exchange of foods between the new and old worlds