Cicero, Academica 2.2:
Lucullus had a certain divine memory for facts – Hortensius had a greater memory for words. But since facts are more advantageous than words in arguing a case, Lucullus’ memory was more preeminent. They say that the memory of Themistocles, whom we set down as easily the best of the Greeks, was singular. One day, when someone promised him the art of memory, which was then being offered up for the first time, it is said that Themistocles responded that he would prefer to learn how to forget, no doubt because whatever he had heard or seen was stuck in his memory. Endowed with such a tremendous intellect, Lucullus had even added that instruction which Themistocles which had scorned: and so just as we commit to letters whatever we wish to make a memorial of, so he had all of the facts graven in his mind.
habuit enim divinam quandam memoriam rerum – verborum maiorem Hortensius; sed quo plus in negotiis gerendis res quam verba prosunt, hoc erat memoria illa praestantior. quam fuisse in Themistocle, quem facile Graeciae principem ponimus, singularem ferunt; qui quidem etiam pollicenti cuidam se artem ei memoriae, quae tum primum proferebatur, traditurum respondisse dicitur oblivisci se malle discere, credo quod haerebant in memoria quaecumque audierat et viderat. tali ingenio praeditus Lucullus adiunxerat etiam illam quam Themistocles spreverat disciplinam; itaque ut litteris consignamus quae monimentis mandare volumus sic ille in animo res insculptas habebat.