History of the Peloponnesian War

If we turn to our military policy, there also we differ from antagonists. We throw open our city to the world, and never by alien acts exclude foreigners from any opportunity of learning or observing, although the eyes of an enemy may occasionally profit by our liberality; trusting less in system and policy than to the native spirit of our citizens; while in education, where our rivals from their very cradles by a painful discipline seek after manliness, at Athens we live exactly as we please, and yet are just as ready to encounter every legitimate danger.

In proof of this it may be noticed that the Lacedaemonians do not invade our country alone, but bring with them all their confederates; while we Athenians advance unsupported into the territory of a neighbor, and fighting upon a foreign soil usually vanquish with ease men who are defending their homes.