Cicero De Finibus 2 104-5
“What kind of sense, then, is there to the idea that a wise person should not let go of good memories but forget bad ones? First, is what we remember under our control? Themistocles, it is said, when Simonides promised to teach him the art of memory, responded, “I’d prefer learning to forget. For I remember things I wish I didn’t and I can’t forget the things I want to.” [Epicurus] was a man of great insight, but the fact us that a philosopher who prohibits remembering asks too much of us.”
Iam illud quale tandem est, bona praeterita non effluere sapienti, mala meminisse non oportere? Primum in nostrane est potestate quid meminerimus? Themistocles quidem, cum ei Simonides an quis alius artem memoriae polliceretur, ‘Oblivionis,’ inquit, ‘mallem; nam memini etiam quae nolo, oblivisci non possum quae volo.’ Magno hic ingenio; sed res se tamen sic habet ut nimis imperiosi philosophi sit vetare meminisse.