1. Aristotle, , Books I, III, VIII — servile vs. liberal activity, the laboring classes and citizenship
2. Thomas Aquinas, , II-II, Q. 187 — the natural obligation to work and the dignity of manual labor
3. John Locke, , Chapter V — labor as the source of property and value
4. Jean-Jacques Rousseau, , Part II — property, labor, and the origins of social inequality
5. Adam Smith, , Books I–II — the division of labor, the labor theory of value, and its social costs
6. Karl Marx, , Volume I; — alienated labor, surplus value, and the liberation of the proletariat
7. John Stuart Mill, ; , Book IV — labor's political rights and the case for worker cooperation
8. Thomas Aquinas, , II-II, Q. 66 — just wages and the laborer's right to the product of work