Ella, che ben conosce in quel paese
Qual più secreta sia virtù ne l'herba
E con qual succo ne le carni offese
Mitighi il duol d'ogni ferita acerba
(Arte gentil che da la madre apprese,
Di cui memoria et uso anco riserba),
Vorria di sua man propia a le ferute
Di chi 'l cor le ferìo recar salute.
She, who perfectly knows, in that land,
The most secret powers of the herbs
And which juice, in the wounded flesh,
Can soothe the pain of an open wound
-- A noble art she learned from her mother,
Of which she keeps the memory and use --
Would like, with her own hands, to give health
To the wounds of him who wounded her heart.
Here's the other side of the women's magic/medical skills in the Renaissance: either the -- alleged -- evil powers of wicked plotters (see Armida), often belonging to the lower classes, or notions about health care and cosmetics being transmitted orally between women usually belonging to the upper classes, e.g. Lucrezia Borgia.
In the parallel episode in Gerusalemme Liberata (6: 67), Erminia i.e. Nicaea was also told to have learned carmi, incantations, from her mother. Here in the Conquistata, Tasso avoids any risk of mixing up white and black magic. But words were anyway "needed" when applying herbs, perhaps reciting the Lord's Prayer instead of a heathen formula.
In the final printed text of GC some words in this stanza were changed, though not altering the general sense; however, the wording in the manuscript was even more effective and has been preserved here.