Smith ends TMS by promising to follow it up with a book on justice. Justice is the only virtue that can and should be expressed in precise rules, he believes, and he believes also that a set of these rules, or principles for generating such rules, should provide “the foundation of the laws of all nations.” The theory of natural justice is clearly the main link between moral philosophy and political philosophy, for Smith. Smith’s language for a world without justice readily evokes Hobbes. From the perspective of theorists of justice, and perhaps from God’s perspective, the purpose (“final cause”) of systems of justice is the preservation of society. Smith’s treatment of justice as an individual virtue does have some implications for how the people think about what they call “social justice,” however. Some recent commentators have argued that there is a notion of fundamental human equality built into Smith’s entire approach to morality.