I spent some of the recent holiday in Florence, visiting many of the amazing Renaissance buildings, whilst reading a great historical novel about the rise and fall of the Medici bankers in the 15th century.
The book is called Medici Money written by Tim Parks, and traces the fame and fortune of five generations of Medici from the original founder of the bank Giovanni di Bicci de Medici (1360-1429) to his great-great-grandson Piero (1472-1503) who ruined the bank when he fled Florence in fear of the French, who invaded in 1494.
The banks rise was based upon dealing with the challenge of usury. Making interest on loans was considered a mortal sin by the Church, and would result in a sentence to burn in hell should the perpetrator be caught in such acts.
As a result, people found ways around it.