[IAUOLENUS libro decimo epistularum. ] §46.1.42.prSi ita fideiussorem accepero: 'quod ego decem credidi, de ea pecunia mille modios tritici fide tua 'esse iubes?', non obligatur fideiussor, quia in aliam rem, quam quae credita est, fideiussor obligari non potest, quia non, ut aestimatio rerum quae mercis numero habentur in pecunia numerata fieri potest, ita pecunia quoque merce aestimanda est.
[JAVOLENUS, in the tenth book of Letters.] If I accept a surety in this manner: "As to the ten which I have lent, do you authorize one thousand modii of wheat to be on your guarantee for that money?", the surety is not bound; because a surety cannot be bound for a different thing than that which was lent, because just as the valuation of things which are considered as merchandise can be made in cash, it does not follow that money also must be valued in merchandise.