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

50. Meanwhile Gylippus and Sicanus returned to Syracuse. Sicanus had not succeeded in his¹ design upon Agrigentum; for while he was at Gela on his way the party indined to friendship with the Syracusans had been driven out. But Gylippus brought back a large army, together with the hoplites who had been sent in merchant-vessels from Peloponnesus in the spring², and had come by way of Libya to Selinus. [2] They had been driven to Libya by stress of weather, and the Cyrenaeans had given them two triremes and pilots. On their voyage they had made common cause with the Evesperitae, who were besieged by the Libyans.

After defeating the Libyans they sailed on to Neapolis, a Carthaginian factory which is the nearest point to Sicily, the passage taking two days and a night only; thence they crossed and came to Selinus. [3] On their arrival, the Syracusans immediately prepared to renew their attack upon the Athenians, both by land and sea. And the Athenian generals, seeing that their enemy had been reinforced by a new army, and that their own affairs, instead of improving, were daily growing worse in every respect, and being especially troubled by the sickness of their troops, repented that they had not gone before. Even Nicias now no longer objected, but only made the condition that there should be no open voting. So, maintaining such secrecy as they could, they gave orders for the departure of the expedition; the men were to prepare themselves against a given signal. [4] The preparations were made and they were on the point of sailing, when the moon, being just then at the full, was eclipsed. The mass of the army was greatly moved, and called upon the generals to remain. Nicias himself, who was too much under the influence of divination and such like, refused even to discuss the question of their removal until they had remained thrice nine days, as the soothsayers prescribed. This was the reason why the departure of the Athenians was finally delayed.