History of the Peloponnesian War

Ath.The security of such as are at wars consisteth not in the good will of those that are called to their aid, but in the power of those means they excel in. And this the Lacedaemonians themselves use to consider more than any; and therefore, out of diffidence in their own forces, they take many of their confederates with them, though to an expedition but against their neighbours. Wherefore it is not likely, we being masters of the sea, that they will ever pass over into an island.