For nothing stands out so conspicuously, or remains so firmly fixed in the memory, as something in which you have blundered.

[Nihil est enim tam insigne, nec tam ad diuturnitatem memoriae stabile, quam id, in quo aliquid offenderis.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

De Oratore [On the Orator, On Oratory], Book 1, ch. 28 (1.28) / sec. 129 (55 BC) [tr. Sutton/Rackham (1940)]
    (Source)

(Source (Latin)). Alternate translations:

For nothing makes so remarkable, so deep an impression upon the memory as a miscarriage.
[tr. Guthrie (1755)]

For nothing makes so remarkable, so deep an impression upon the memory as a defect.
[Source (1808)]

Nothing, indeed, is so much noticed, or makes an impression of such lasting continuance on the memory, as that in which you give any sort of offense.
[tr. Watson (1860)]

For nothing so immediately attracts attention, or clings so tenaciously to the memory, as any defect.
[tr. Calvert (1870)]

For nothing, we know, strikes us so forcibly or makes such an indelible impression on the memory as that which somehow offends our taste.
[tr. Moor (1892)]

Nothing attracts so much attention, or retains such a hold upon men's memories, as the occasion when you have made a mistake.
[ed. Harbottle (1906)]

For nothing is so conspicuous or so indelibly imprinted on the memory as something that annoys you in any way.
[tr. May/Wisse (2001)]