Strabo Geography 14.1.32

[32] Before coming to Erythrae, one comes first to a small town Erae belonging to the Tëians; and then to Corycus, a high mountain, and to a harbor at the foot of it, Casystes, and to another harbor called Erythras, and to several others in order thereafter. The waters along the coast of Mt. Corycus, they say, were everywhere the haunt of pirates, the Corycaeans, as they are called, who had found a new way of attacking vessels; for, they say, the Corycaeans would scatter themselves among the harbors, follow up the merchants whose vessels lay at anchor in them, and overhear what cargoes they had aboard and whither they were bound, and then come together and attack the merchants after they had put to sea and plunder their vessels; and hence it is that we call every person who is a busybody and tries to overhear private and secret conversations a Corycaean; and that we say in a proverb: when one thinks that he is doing or saying something in secret, but fails to keep it hidden because of persons who spy on him and are eager to learn what does not concern them.

[32] But before we come to Erythrae, the first place we meet with is Erae, ¹ a small city belonging to the Teians.

Next is Corycus, a lofty mountain; and below it, Casystes, a port; ² then another, called the port of Erythrae, and afterwards many others. It is said that the whole sea-coast along the Corycus was the haunt of pirates, who were called Corycaeans, and who had contrived a new mode of attacking vessels. They dispersed themselves among the ports, and went among the merchants who had just arrived, and listened to their conversation respecting the freight of their ships, and the places whither they were bound. The pirates then collected together, attacked the merchants at sea, and plundered the vessels. Hence all inquisitive persons and those who listen to private and secret conversation we call Corycaeans, and say proverbially, when any one thinks that he has done or said anything not to be divulged, but is betrayed by spies or persons anxious to be informed of what does not concern them.