In 1751, at the age of 28, Adam Smith was elected Professor of Logic at the University of Glasgow. And a year later, on this day, 22 April, he was chosen as Professor of Moral Philosophy, and he would remember the period of 13 years in which he held this post as the most useful and happy of his life.

Apart from some quite detailed student notes, little more survives of his lectures than was distilled into The Theory of Moral Sentiments and The Wealth of Nations. But we know that he divided his course into Natural Theology, Ethics, Justice (and Jurisprudence), and Politics.

It was this last element, Politics, that would take his thoughts into the political institutions relating to commerce that would build into The Wealth of Nations; while the Ethics section became the foundation of the book that made his name, The Theory of Moral Sentiments

On the subject of Justice, Smith aimed to write a system of natural jurisprudence, a "theory of the general principles which ought to run through and be the foundation of the laws of all nations". But too soon, he would be headhunted as private tutor to the Duke of Buccleuch and whisked off on the Grand Tour of Europe, which in turn led to him getting absorbed in the vast treatise on economics that dominated the rest of his intellectual life.

The loss of Smith's system of jurisprudence has been a costly one. For there are far too many political leaders around today, even in supposedly democratic countries, who believe that they can (and should) re-cast their laws and constitutions to suit their own particular view of justice. The cost of such conceit has sometimes been a huge increase in human misery and a huge reduction in human freedom. How different the world might be, had we been given that powerful volume by Smith, telling us in his own resonant words what justice really is.