History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
for in point of money, since they were supporting a mercenary force and at the same time bearing the expense of patrol guard-posts, and had now for a year been maintaining a large fleet besides, they were already embarrassed, and hereafter would be quite without resources;[*](Or, “were in some respects already ill-provided, and in still others would be utterly at a loss what to do.”) indeed, they had spent two thousand talents already and were in debt for many talents more, and if they should lose any portion whatsoever of their present force by not being able to pay for its maintenance, their cause would be ruined, since it depended upon mercenary troops and had not, like their own, the backing of necessity.[*](ie. mercenary troops had to be bribed, but the Athenians were compelled to fight.)
They ought, therefore, he concluded, to stay on and continue the siege, and not go back home beaten by money, in which they had by far the greater resources.
To such effect Nicias spoke with confidence, because he had accurate knowledge of affairs in Syracuse, both of their lack of money and that a party existed there that wished the government to come under the control of the Athenians and was constantly making overtures to him to keep him from withdrawing; and at the same time, though beaten in the field, he had as much confidence as ever in the fleet at any rate.
Demosthenes, however, would not consent on any consideration whatever to continue the siege; if they could not lead the army home without a vote of the Athenians, but must stay on in Sicily, he said that they should do this only after removing to Thapsus or to Catana. From this new base they could overrun with their army large tracts of the country and support themselves by ravaging the enemy's property, and at the same time do him damage; and as for the fleet, they would thenceforth do their fighting, not in a narrow space, which was more in the enemy's favour, but in the open sea, where there was plenty of room and the advantages of skill would be on their side, and they would not have to make their retreats and advances setting out from and falling back into a scant and circumscribed base.