11. This latter case (n. 10) represents that putting of money out to interest, which is an essential feature of modern commerce. The former case (n. 9) is the aspect that money-lending commonly bore in the Middle Ages. In those days land was hard to buy, agriculture backward, roads bad, seas unnavigable, carrying-trade precarious, messages slow, raids and marauders frequent, population sparse, commerce confined to a few centres, mines unworked, manufactures mostly domestic, capital yet unformed. Men kept their money in their cellars, or deposited it for safety in religious houses: whence the stories of treasure-trove belonging to those days. They took out the coin as they wanted it to spend on housekeeping, or on war, or feasting. It was very hard, next to impossible, to lay out money so as to make more money by it. Money was in those days really barren--a resource for housekeeping, not for trade--a medium of private, not of commercial exchange--a representative of use value, not of market value. Apart from risk of non-repayment, to take interest for money that you had no use for but to hoard, was getting "a breed of barren metal:" it was taking up what you laid not down: it was making profit out of your neighbour's need, or your neighbour's gain, where there was no corresponding need unsatisfied, or gain forfeited, on your part: it was that "attempt to draw profit and increment, without labour, without cost, and without risk, out of the use of a thing that does not fructify," which the Fifth Lateran Council defines to be usury. 12. In our time, thanks to steam and electricity, the increase of population, and continued peace, the whole world has become one trading community, representing now more, now less abundant opportunities for the investment of money, and the conversion of it into other lucrative commodities. Money consequently with us is not a mere medium of private exchange for the purposes of housekeeping: it is a medium of commercial exchange. It represents, not use value, but market value. To be a thousand pounds out of pocket for a year means an opportunity of gain irretrievably lost, gain that could have been made otherwise than by money-lending. Where this is so, and so far as it is so, the lender may without violation of justice point to _lucrum cessans_, gain lost, and arrange beforehand with the borrower for being reimbursed with interest.