Read the excerpt from "Hokusai's The Great Wave” by Neil MacGregor.
In the early nineteenth century Japan had been effectively closed off from the world for 200 years. It had simply opted out of the community of nations.
Kings are burning somewhere,
Wheels are turning somewhere,
Trains are being run,
Wars are being won,
Things are being done
Somewhere out there, not here.
Here we paint screens.
Yes . . . the arrangement of the screens.
This is Stephen Sondheim’s musical tableau of the secluded and calmly self-contained country in 1853, just before American gunships forced its harbours to open to the world. It is a witty caricature of the dreamy and aesthetic Japanese, serenely painting screens while across the seas Europe and America industrialize and political turmoil rages.

What is the purpose of the outside source used in this excerpt?
A )to illustrate Japan’s isolation in the 1800s
B) to educate readers about Japanese screens
C) to introduce readers to a musical by Stephen Sondheim
D) to argue against American aggressiveness

The author starts the paragraph by telling us that Japan was isolated during the 1800s. He goes on to introduce an outside source (Stephen Sondheim's musical tableau) as a way to back up this assertion. Although this might seem unnecessary, his reason for including it is to illustrate Japan's isolation during this time period. The source shows how other countries thought about Japan's situation, and it provides evidence for the author's claim.