Lexitechnia

Pseudo-Quintilian (Declamatio Maior 14.9):

Illa vera sunt remedia, quæ fugatis morbis causisque languoris postea non sentiuntur, et ea tantum innocenter dabuntur, quæ potentiæ suæ qualitate consumpta desinunt, cum profuerunt.

Real cures are those which are no longer felt after the diseases and the causes of weakness have been driven out; and only those which stop working after they have used up whatever kind of effect they have can be given without any harm.

I wasn’t sure whether consumpta “used up, consumed” was supposed to go with quæ [remedia] or with qualitate as an ablative absolute.  The latter make more sense, but I think chiefly I chose it because it made a less awkward translation.

I wasn’t able to find a reference translation of the Declamationes Maiores online to check this against, but the medical metaphor is pretty clear.

[For qualitas.]