[IDEM libro secundo definitionum. ] §12.6.59.prSi fideiussor iure liberatus soluerit errore pecuniam, repetenti non oberit: si uero reus promittendi per errorem et ipse postea pecuniam soluerit, non repetet, cum prior solutio, quae fuit irrita, naturale uinculum non dissoluit, nec ciuile, si reus promittendi tenebatur.
[THE SAME, in the second book of Definitions.] If a guarantor who has been legally discharged should pay money by mistake, it will not prevent him from recovering it; but if the principal debtor himself should also subsequently pay the money by mistake, he will not recover it, since the prior payment, which was void, did not dissolve the natural obligation, nor the civil obligation if the principal debtor was bound.