The 5th century bc Athenian historian Thucydides proposed that the driving force behind interstate relations was power and fear. But the soldier-essayist Xenophon (d. 354 bc) thought that humiliation, of the sort that the EU recently heaped on Mrs May, lay at the heart of the problem.

In his Cyropaedia, Xenophon wrote an extended essay on the achievements of the Persian King Cyrus the Great (d.