In the same summer William Adam, a nephew of the architect, conversed with Smith upon Bentham’s letters on usury. The economist is reported to have said that “the _Defence of Usury_ was the work of a very superior man, and that though he had given him some hard knocks, it was done in so handsome a way that he could not complain.”[51] It is quite possible that had Smith lived to see another edition of the _Wealth of Nations_ through the press, he would have responded to Bentham’s invitation by admitting the futility of fixing interest by law. But at this time he was still busy with the sixth edition of the _Moral Sentiments_, which at last appeared early in the following year. In the preface he referred to the promise he had made in 1759 of a treatise on Jurisprudence. That promise had been partially fulfilled in the _Wealth of Nations_; but what remained, the theory of Jurisprudence, he had hitherto failed to execute. “Though my very advanced age leaves me,” he acknowledged, “very little expectation of ever being able to execute this great work to my own satisfaction, yet, as I have not altogether abandoned the design, and as I wish still to continue under the obligation of doing what I can, I have allowed the paragraph to remain as it was published more than thirty years ago, when I entertained no doubt of being able to execute everything which it announced.” These words were probably written late in the year 1789. In February 1790 he told Lord Buchan, “You will never see your old friend any more. I find that the machine is breaking down.” From this time he rapidly wasted away, and in June his friends knew, as well as he did, that there was no hope of recovery. His intellect remained perfectly clear, and he bore his sufferings with the utmost fortitude and resignation.