O clear and noble conscience, how sharply a little fault stings you!

[O dignitosa coscïenza, e netta,
come t’è picciol fallo amaro morso!]

Dante Alighieri the poet
Dante Alighieri (1265-1321) Italian poet
The Divine Comedy [Divina Commedia], Book 2 “Purgatorio,” Canto 3, l. 8ff (3.8-9) (1314) [tr. Kline (2002)]
    (Source)

Observing his guide, Virgil, upset over one of his own lapses.

(Source (Italian)). Alternate translations:

O matchless dignity of stainless thought!
Thus bitter seems to you the taste of Sin!
[tr. Boyd (1802), st. 2]

O clear conscience and upright
How doth a little sting wound thee sore!
[tr. Cary (1814)]

Oh, dignity of conscience, when complete,
How small will bitter make that once was sweet!
[tr. Bannerman (1850)]

O noble conscience, and without a stain,
How sharp a sting is trivial fault to thee!
[tr. Longfellow (1867)]

O conscience, dignified and pure, how bitter a sting is a small fault to thee!
[tr. Butler (1885)]

O conscience honourably pure, to thee
How is a little fault most bitterly shrived!
[tr. Minchin (1885)]

O conscience, upright and stainless, how bitter a sting to thee is little fault!
[tr. Norton (1892)]

O noble conscience and clear, how sharp a sting gives a little fault to thee!
[tr. Wicksteed (1899)]

O pure and noble conscience, how bitter a sting to thee is a little fault!
[tr. Sinclair (1939)]

O honourable conscience, clear and chaste,
How small a fault stings thee to bitter smart!
[tr. Binyon (1943)]

O noble conscience, clear and undefaced,
How keen thy self-reproach for one small slip!
[tr. Sayers (1955)]

O noble conscience without stain! how sharp
the sting of a small fault is to your sense!
[tr. Ciardi (1961)]

O pure and noble conscience, how bitter
a sting is a little fault to you!
[tr. Singleton (1973)]

O dignity of conscience, noble, chaste,
how one slight fault can sting you into shame!
[tr. Musa (1981)]

O conscience so precious and so clear,
How small a fault is a sharp tooth to you!
[tr. Sisson (1981)]

O pure and noble conscience, you in whom
each petty fault becomes a harsh rebuke!
[tr. Mandelbaum (1982)]

O worthy clear conscience, how bitter a bite to you is even a little fault!
[tr. Durling (2003)]

Such dignity of conscience, clear and clean,
bitten so keenly by so slight a fault!
[tr. Kirkpatrick (2007)]

O pure and noble conscience,
how bitter is the sting of your least fault!
[tr. Hollander/Hollander (2007)]

But O, how purest consciences are stung
By tiny faults, bitter on noble tongues!
[tr. Raffel (2010)]