The development of sea trade was made possible due to the simultaneous development of "bank" credit, which was gradually made known through two quite different institutions: the temple and the bank in the agora.

Only wealthy landowners were in position to lend those who wished to engage in trade. They had at their disposal the necessary funds to build or buy a ship and cargo. Citizens coming from poor social classes and former aristrocrats who had been economically ruined, fell back on borrowing, in order to bring any ambitious plans they had to fruition.