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.
But when the navy of Minos had been established, navigation between various peoples became saferfor the evil-doers on the islands were expelled by him, and then he proceeded to colonize most of them—and the dwellers on the sea-coast now began to acquire property more than before and to become more settled in their homes, and some, seeing that they were growing richer than before, began also to put walls around their cities.
Their more settled life was due to their desire for gain; actuated by this, the weaker citizens were willing to submit to dependence on the stronger, and the more powerful men, with their enlarged resources, were able to make the lesser cities their subjects.
And later on, when they had at length more completely reached this condition of affairs, they made the expedition against Troy.
And it was, as I think, because Agamemnon surpassed in power the princes of his time that he was able to assemble his fleet, and not so much because Helen's suitors, whom he led, were bound by oath to Tyndareus.[*](According to the post-Homeric legend, all who paid their court to Helen engaged to defend the man of her choice against all wrong. cf. Isoc. 10.40; Paus. 3.20. 9; 3.10.9.)