The Wealth of Nations by Part 5 Chapter 1 Page 88

the increasing business of the society, in consequence of its increasing improvement. The administration of justice became so laborious and so complicated a duty as to require the undivided attention of the persons to whom it was entrusted.

The person entrusted with the executive power not having leisure to attend to the decision of private causes himself, a deputy was appointed to decide them in his stead. In the progress of the Roman greatness, the consul was too much occupied with the political affairs of the state to attend to the administration of justice. A praetor, therefore, was appointed to administer it in his stead. In the progress of the European monarchies which were founded upon the ruins of the Roman empire, the sovereigns and the great lords came universally to consider the administration of justice as an