According to Mark Blyth, the concept of austerity emerged in the 20th century, when large states acquired sizable budgets. However, Blyth argues that the theories and sensibilities about the role of the state and capitalist markets that underline austerity emerged from the 17th century onwards. Austerity is grounded in liberal economics' view of the state and sovereign debt as deeply problematic. Blyth traces the discourse of austerity back to John Locke's theory of private property and derivative theory of the state, David Hume's ideas about money and the virtue of merchants, and Adam Smith's theories on economic growth and taxes. On the basis of classic liberal ideas, austerity emerged as a doctrine of neoliberalism in the 20th century.