the Knee Plays is like a sub-story that is woven through the tapestry of the CIVIL warS. Each play serves as an introduction to the longer scene that follows. the CIVIL warS has a subtitle, “a tree is best measured when it is down.” This is an old American folksaying which Carl Sandburg used for the title of his chapter on the death of Abraham Lincoln. The tree in the first knee play is meant to be a tree of life, perhaps in Africa, thought to be the origin of man.
The cabin being built in the second Knee Play leads to the second scene of the opera (in Holland) in which one sees a cabin that is being constructed. In the fourth Knee Play you see a bird that takes a man from the deck of the boat and flies away with him. This leads to a scene in France in which various historical characters are seen in the sky. In another knee play you see the cabin of the boat floating ashore with Admiral Perry on his second voyage to Japan which leads into a scene with Japanese actors performing contemporary theatre while Abraham Lincoln observes from a box high in the air.
Later you see the hull of the boat sinking beneath the sea which leads into the first scene of the third act which is a voyage under the sea, a Jules Verne voyage with Captain Nemo. Eventually, you see the hull of the boat dragged ashore during the American Civil War which leads into a scene which depicts many tents before a battle during the American Civil War.
So, they serve in some cases as an introduction to the larger scenes, but on their own they tell a story together than can be seen separately. When you see them in the larger context they make another sense. For example, the first knee play is a man in a tree and a lion beneath the tree. In the final scene of the opera (which is in Rome), Hercules descends from the sky, and he is depicted as a man wearing a lion skin. In the final moments of the opera we are in a jungle, a tropical jungle, and that original tree from the first knee play which we depicted very abstractly, appears again more realistically in this setting with Hercules singing with a chorus of animals. In this way, the piece is woven together like a piece of tapestry.