CS Lewis on Christian Economics

There is one bit of advice given to us by the ancient heathen Greeks, and by the Jews of the Old Testament (sort of–JBA), and by the great Christian thinkers of the Middle Ages, which the modern economic system has completely disobeyed.  All these people told us not to lend money at interest:  and lending money at interest–what we call investment–is the basis of our whole system…

The three great civilizations had agreed (or so it seems at first sight) on condemning the very thing on which we have based our whole life

Mere Christianity, 81-82