The central idea was not a new one,

The central idea was not a new one, indeed the danger from Athens' expansion was bound to be a topic of discussion and even of noisy indignation among the Peloponnesians, in no sense secret, so that it could hardly fail to find its way into a responsible account of their deliberations. What, then, of to be least spoken of and to be stated in public? Is it not, still, eccentric to announce in advance that this theme was not discussed in public, when the speeches which in fact discuss it were, in my belief, already written and Thucydides had no intention of cancelling them?