From Chapter 23, "The Siege of Syracuse (414)" of The Peloponnesian War by Donald Kagan (2003):

Most historians agree with Thuciydides in blaming the continuation of the Sicilian campaign on the greed, ignorance, and foolishness of the direct Athenian democracy. But the behavior of the Athenians on this occasion is the opposite of the flighty indecision that is usually imputed to their democracy. They showed constancy and determination to carry through what they had begun, in spite of setbacks and disappointments. Their error, in fact, is one common to powerful states, regardless of their constitutions, when they are unexpectedly thwarted by an opponent they anticipated would be weak and easily defeated. Such states are likely to view retreat as a blow to their prestige, and while unwelcome in itself, it is also an option that puts into question their strength and determination and with it their security. Support for ventures such as the Sicilian campaign generally remains strong until the prospect of victory disappears.

TopicSociety - TopicLiterature - 2007-04-03

(correlates: PeloponnesianWar, Lowly, Lowly Cook, HowToDiscreditAnUnwelcomeReport, ...)