What does "nescit labi virtus" mean in English?

Question

I assume it's latin. It's part of my family crest. I know that Virtus in latin is Virtue.

Answer 1

Virtus can certainly be translated as virtue, excellence,
courage
nescit = knows not, is ignorant of.. (from nescio..)
labi = to slip, slide, sink, go to ruin (from labor..)

So you could render the phrase as "Virtue knows nothing of sliding into ruin" or

"excellence cannot perish"

Answer 2

Difficult. (Labes, labis) is defined as (1) a falling, ruin, destruction, or downfall; and (2) a blot, stain, or blemish.

"Virtue knows of no imperfection" is the general sense, but there are several possible shades of meaning. Virtue puts the best possible interpretation on everything it sees? Virtue does not know how to be non-virtuous? Virtue does not have moments of being non-virtuous? Until you have the sense of the original, you cannot pick the correct translation.

Answer 3

Juan Valera (1824–1905). Pepita Jimenez.
The Harvard Classics Shelf of Fiction. 1917.

Pepita Jiménez: Discovery of the Manuscript

“NESCIT LABI VIRTUS”


THE REVEREND Dean of the Cathedral of ——, deceased a few years since, left among his papers a bundle of manuscript, tied together, which, passing from hand to hand, finally fell into mine, without, by some strange chance, having lost a single one of the documents contained in it. Inscribed on this manuscript were the Latin words I use above as a motto, but without the addition of the woman’s name I now prefix to it as its title; and this inscription has probably contributed to the preservation of the papers, since, thinking them, no doubt, to be sermons, or other theological matter, no one before me had made any attempt to untie the string of the package, or to read a single page of it. 1
The manuscript is in three parts. The first is entitled “Letters from my Nephew”; the second, “Paralipomena”; and the third, “Epilogue—Letters from my Brother.”