them in awe. We have attained a condition in which a state is able to enforce a legal and peaceful attitude in its own individual citizens towards each other. The state is the guardian of its citizens' peace, but the old problem recurs: Quis custodiet ipsos custodes?
It is obvious that this difficulty increases as the size of states increases. To compel a small state to keep the peace by absorbing it if it fails to do so is always an easy and even tempting process to a neighbouring larger state. This process was once carried out on a complete scale, when practically the whole known world was brought under the sway of Rome. "War has ceased," Plutarch was able to declare in the days of the Roman Empire, and, though himself an enthusiastic Greek, he was unbounded in his admiration of the beneficence of the majestic Pax Romana, and never tempted by any narrow spirit of patriotism to desire the restoration of his own country's glories. But the Roman organization broke up, and no single state will ever be strong enough to restore it.
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