Chapter B–XVIII: Exchanging moneys

Abstract

We have already met in A.60–71 the gold coin used in mediaeval Spain, the morabitinus. We shall now encounter it again, but this time in connection with problems of exchange: a certain number of morabitini are to be converted either into nummi or into solidi —which is only formally different since the solidus is equivalent to a fixed amount of twelve nummi.† Since, however, the coinage was local, the relative values of morabitini and nummi were local as well, but the wide circulation of coins made it likely that an exchange would involve morabitini and nummi of unequal values. Thus, a problem of exchange between these two types of coins in its most general form would involve a quantity m of morabitini of l different kinds to be converted into a quantity q of nummi (or solidi) of n different types, or inversely.