I am exploring the development of the idea that morality or justice for the state is different from morality or justice for the individual, as it appears for example in the work of Machiavelli. I thought I would find this quotation in the Melian dialogue, which makes that kind of point, but I couldn't find the particular quotation I was looking for. I recall that it is a quotation that the ancient historian Geoffrey de Ste Croix attached much significance to. Can anyone help please by providing the reference in Thucydides?