History of the Peloponnesian War

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.