History of the Peloponnesian War

For if the city of the Lacedaemonians were laid desolate, and the temples and foundations of the public buildings were left, I think that when a long time had passed by, posterity would have great disbelief of their power in proportion to their fame. (And yet they occupy two of the five divisions of the Peloponnese, and take the lead of the whole of it, and of their allies out of it in great numbers. Still, as the city is neither built closely, nor has sumptuous temples and public buildings, but is built in villages, after the old fashion of Greece, it would have an inferior appearance.) Whereas if the Athenians were to suffer the same fate, I think their power would be conjectured, from the appearance of the city to the eye, to have been double what it is.

It is not therefore right to be incredulous, nor to look at the appearance of cities rather than their power; but to think that that expedition was greater indeed than any that were before it, but inferior to those of the present day; if on this point again we must believe the poetry of Homer, which it is natural that he, as a poet, set off on the side of exaggeration; but, nevertheless, even on this view it appears inferior.