History of the Peloponnesian War

Then you ought to have introduced them for aid against us alone, and not to have joined with them in attacking others; such a course having certainly been open to you, in case of your being at all led on by the Athenians against your will, since the confederacy against the Mede had already been formed by these Lacedaemonians here, which you yourselves bring forward most prominently [in your own defence]. Surely this was strong enough to divert us from attacking you, and, what is the greatest advantage, to enable you to take counsel in security. But of your own accord, and not by compulsion, you still took the part of the Athenians by preference.

And you say that it had been base for you to betray your benefactors; but much more base and criminal was it so utterly to betray the whole body of the Greeks, with whom you confederated, than to give up the Athenians alone, who were enslaving Greece, while the others were its liberators.