In this margin of uncertainty we have only common sense to guide us, as in every other similar case. We know pretty well in each particular example we come across whether a loan is productive of not; whether we are borrowing or lending for a productive purpose, or for a charitable or luxurious one, or for one in every way unproductive. The proof that this feeling about usury is right is to be found in the private conduct of individuals in their social relations. If a poor man in distress goes to a rich friend and borrows ten pounds, he pays it back when he can; and the rich man would think it dishonourable to charge interest. But if a man borrowed ten pounds of one for the purpose of doing something which was likely to increase its value, and we knew that this was his purpose, we should have a perfect right to share the results with him, and no one would think the claim dishonourable. Usury, then, is essentially a claim to increment, or extra wealth, _which is not there to be claimed_. It is a practice which diminishes the capital wealth of the needy and eats it up to the profit of the lender; so that, if usury go unchecked, it must end in the absorption of all private property into the hands of a few money brokers. Now, these things being so, the nature of usury being pretty clear, and both the moral wrong of it and the injury it does to society being equally clear, how is it that the modern world for so long forgot all about it, and how is it that it is forcing itself upon the attention of the modern world again in spite of that forgetfulness? I will answer both of those questions.