A Note on the 630 Ducats
When money was worth the metal it was made of, the value of a coin depended on three things: the type of metal, its purity and its weight. A ducat (Latin ducatus and a florin (Latin florenus, German gulden) were both made of gold and both of the same weight, but they differed in purity. The purity of a ducat was 23 2/3 carats (that is, virtually 100%) while that of a florin was 18 carats and 6 grains (that is, just over 75%). 600 ducats were therefore worth 800 florins and the offer of 630 ducats to cover a debt of 800 florins is equivalent to the entire sum in hard currency plus five percent.