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

27. When the Athenians heard that their own army was suffering and that supplies were introduced¹ into the island, they began to be anxious and were apprehensive that the blockade might extend into the winter. They reflected that the conveyance of necessaries round the Peloponnese would then be impracticable. Their troops were in a desert place, to which, even in summer, they were not able to send a sufficient supply. The coast was without harbours; and therefore it would be impossible to maintain the blockade. Either the watch would be relaxed and the men would escape; or, taking advantage of a storm, they might sail away in the ships which brought them food. [2] Above all they feared that the Lacedaemonians, who no longer made overtures to them, must now be reassured of the strength of their own position, and they regretted having rejected their advances. [3] Cleon, knowing that he was an object of general mistrust because he had stood in the way of peace, challenged the reports of the messengers from Pylos; who rejoined that, if their words were not believed, the Athenians should send commissioners of their own. And so Theogenes and Cleon himself were chosen commissioners. [4] As he knew that he could only confirm the report of the messengers whom he was calumniating, or would be convicted of falsehood if he contradicted them, observing too that the Athenians were now more disposed to take active measures, he advised them not to send commissioners, which would only be a loss of valuable time, but, if they were themselves satisfied with the report, to send a fleet against the island. [5] Pointedly alluding to Nicias the son of Niceratus, who was one of the generals and an enemy of his, he declared sarcastically that, if the generals were men, they might easily sail with an expedition to the island and take the garrison, and that this was what he would certainly have done, had he been general.