History of the Peloponnesian War

"Again if we had all remained independent we should have had better assurance that they would make no violent change in our status; having, however, the majority under their hands, while still associating with us on an equal footing, they would naturally find it more irksome that our state alone still maintained its equality as compared with the majority that had already yielded, especially since they were becoming more powerful in proportion as we became more isolated.

Indeed it is only the fear that arises from equality of power that constitutes a firm basis for an alliance; for he that would transgress is deterred by the feeling that he has no superiority wherewith to make an attack.

And we were left independent for no other reason than because they clearly saw that with a view to empire they must get control of affairs by fair-seeming words and by attacks of policy rather than of force.