I have read somewhere or other, — in Dionysius of Halicarnassus, I think, — that history is philosophy teaching by examples.

On the Study and Use of History, letter 2; in fact this relates to a third-century AD treatise on rhetoric, wrongly attributed to Dionysius of Halicarnassus, which says (xi. 2): "The contact with manners then is education; and this Thucydides appears to assert when he says history is philosophy learned from examples". The line is not found in Thucydides.