If one looks at how all this was justified, two things jump out. First, Protestant thinkers all continued to make the old medieval argument about interesse: that “interest” is really compensation for the money that the lender would have made had he been able to place his money in some more profitable investment. Originally, this logic had only been applied to commercial loans. Increasingly, it was now applied to all loans. Far from being unnatural, then, the growth of money was now treated as completely expected. All money was assumed to be capital.
