… is from page 614 of Will Durant’s 1939 volume, The Life of Greece; Durant here describes the historian Polybius (c. 200 BC – c. 118 BC) (footnote deleted):
He is a realist and a rationalist; he pierces the moral phrases of diplomats to the actual motives of policy. It amuses him to observe how easily men can be deceived, singly or en masse, and even repeatedly by the same tricks.