Few merchants could survive by trading in a single item. The varying needs of different economic regions led to the organization of diversified trade. The lands to the north lacked sunshine and wanted wine. The wine-producing countries were generally short of grain. Wool came from England, Spain, Languedoc, or Provence, while alum came from the East or from Italy, and the dyes—woad, indigo, saffron, cochineal, khermes, and roccella or orseille—from a variety of places. Although this situation encouraged reciprocal trade among marketplaces and rotating cargoes, it did not necessarily mean that every single merchant diversified.
Reinvestment of profits provided the first stimulus for universality. Until the development of the money market in the fourteenth century, businessmen had only two alternatives: to ensure the recovery of their earnings or to use their profits to buy goods for the return journey. The first meant leaving the capital idle—for as long as six months in the case of long‐ distance trade—so the choice was obvious.
The introduction of bills of exchange—of banking and the movement of capital—did little to change the basic problem. While it was easy enough to bring money home, nobody was prepared to pay high rates for freight and risk returning without a cargo. Although such voyages were tolerated in certain kinds of trade such as that of salt, where convoys would sometimes return home empty from the Baltic, the business world was nevertheless unanimous in regarding them as a last resort. Once again it was a matter of financial sterility: what was to be gained from leaving capital and ships