We now come to Adam Smith, the founder of modern Political Economy, whether it be treated as a science or as an art. He considered it as an art. “Political Economy,” he says, in the introduction to the fourth book, “proposes two distinct objects: first, to provide a plentiful revenue or subsistence for the people, or, more properly, to enable them to provide such a revenue or subsistence for themselves; and, secondly, to supply the state or common weal with a revenue sufficient for the public service. It proposes to enrich both the people and the sovereign.” The principal purpose of his work was to show the erroneousness of the means by which political economists had proposed to attain these two great objects. And in the then state of knowledge, this could be done only by proving that many of them mistook the nature of wealth, and all of them the laws according to which it is produced and distributed. The scientific portion of his work is merely an introduction to that which is practical. Of the five books into which the work is divided, it occupies only the first and second. The third is an historical sketch of the progress of national opulence. The fourth, the longest in the whole work, considers the direct interferences by which governments have attempted to lead or force their subjects to become rich; and decides, “that every system which endeavours, either by extraordinary encouragements, to draw towards a particular species of industry a greater share of the capital of the society than would naturally go to it, or, by extraordinary restraints, to force from a particular species of industry some share of the capital which would otherwise be employed in it, is in reality subversive of the great purpose which it means to promote. It retards, instead of accelerating, the progress of the society towards real wealth and greatness; and diminishes, instead of increasing, the real value of the annual produce of its land and labour.” “All systems,” he adds, “either of preference or of restraint, therefore, being thus completely taken away, the obvious and simple system of natural liberty establishes itself of its own accord. According to that system, the sovereign has only three duties to attend to: first, the duty of protecting the society from the violence and invasion of other independent societies; secondly, the duty of protecting, as far as possible, every member of the society from the injustice or oppression of every other member of it, or the duty of establishing an exact administration of justice; and, thirdly, the duty of erecting and maintaining certain public works and certain public institutions, which it can never be for the interest of any individual, or small number of individuals, to erect and maintain.”