Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

33. 'I dare say that, like others, I shall not be believed when I tell you that the expedition is really coming; and I am well aware that those who are either the authors or reporters of tidings which seem incredible not only fail to convince others, but are thought fools for their pains. Yet, when the city is in danger, fear shall not stop my mouth; for I am convinced in my own mind that I have better information¹ than anybody. [2] The Athenians, wonder as you may, are coming against us with a great fleet and army; they profess to be assisting their Egestaean allies and to be restoring the Leontines. But the truth is that they covet Sicily, and especially our city. They think that, if they can conquer us, they will easily conquer the rest. [3] They will soon be here, and you must consider how with your present resources you can make the most successful defence. You should not let them take you by surprise because you despise them, or neglect the whole matter because you will not believe that they are coming at all. [4] But to him who is not of this unbelieving temper I say:— And do not you be dismayed at their audacity and power. They cannot do more harm to us than we can do to them; the very greatness of their armament may be an advantage to us; it will have a good effect on the other Sicilian cities, who will be alarmed, and in their terror will be the more ready to assist us. Then, again, if in the end we overpower them, or at any rate drive them away baffled, for I have not the slightest fear of their accomplishing their purpose, we shall have achieved a noble triumph. [5] And of this I have a good hope. Rarely have great expeditions, whether Hellenic or Barbarian, when sent far from home, met with success. They are not more numerous than the inhabitants and their neighbours, who all combine through fear; and if owing to scarcity of supplies in a foreign land they miscarry, although their ruin may be chiefly due to themselves, they confer glory on those whom they meant to overthrow. [6] The greatness of these very Athenians was based on the utter and unexpected ruin of the Persians², who were always supposed to have directed their expedition against Athens. And I think that such a destiny may very likely be reserved for us.