Usury was prohibited in medieval Europe by the Church. Charging interest on a loan was not allowed anywhere in Europe until 1545, when Henry VIII legalised it in England. Bills of exchange first appeared in the 12th century and were used to circumvent this restriction. A bill of exchange was a note for the future exchange of one currency for another. They were gambles on exchange-rate variations. Because profit from them was so uncertain, the Church did not view the profit as a form of interest. Merchants like Francesco Datini used instruments such as bills of exchange to create vast networks of credit spanning the whole of Europe from London to Constantinople. --- **Source:** Gleeson-White, Jane. Double Entry: How the Merchants of Venice Created Modern Finance. New York: W.W. Norton & Co., 2012. http://www.myilibrary.com?id=336325.