But one answer can be glimpsed from a contemporary study, The Rise and Fall of the Great Powers, by Yale historian Paul Kennedy.

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Reopened two years ago after an extensive renovation, the court contains marble and bronze figurative works by 19th and 20th Century American sculptors like Hiram Powers, Augustus Saint-Gaudens and Paul Manship.

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The eminent historian Paul Kennedy wrote a book entitled The Rise and Fall of the Great Powers in which he argued that powerful countries typically undercut their economic strength by trying to control too much territory, leading to their decline.

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