value of a thing is determined by what one is willing to give up to obtain the thing. The body of theory later termed "neoclassical economics" or "marginalism" formed from about 1870 to 1910. The term "economics" was popularised by such neoclassical economists as Alfred Marshall as a concise synonym for "economic science" and a substitute for the earlier, broader term "political economy" used by Smith. This corresponded to the influence on the subject of mathematical methods used in the natural sciences. Neoclassical economics systematised supply and demand as joint determinants of price and quantity in market equilibrium, affecting both the allocation of output and the distribution of income. It dispensed with the labour theory of value of which Smith was most famously identified with in classical economics, in favour of a marginal utility theory of value on the demand side and a more general theory of costs on the supply side. The bicentennial anniversary of the publication of The Wealth of Nations was celebrated in 1976, resulting in increased interest for The Theory of Moral Sentiments and his other works throughout academia. After 1976, Smith was more likely to be represented as the author of both The Wealth of Nations and The Theory of Moral Sentiments, and thereby as the founder of a moral philosophy and the science of economics. His homo economicus or "economic man" was also more often represented as a moral person. Additionally, economists David Levy and Sandra Peart in "The Secret History of the Dismal Science" point to his opposition to hierarchy and beliefs in inequality, including racial inequality, and provide additional support for those who point to Smith's opposition to slavery, colonialism, and empire. Emphasised also are Smith's statements of the need for high wages for the poor, and the efforts to keep wages low. In The "Vanity of the Philosopher: From Equality to Hierarchy in Postclassical Economics", Peart and Levy also cite Smith's view that a common street porter was not intellectually inferior to a philosopher, and point to the need for greater appreciation of the public views in discussions of science and other subjects now considered to be technical. They also cite Smith's opposition to the often expressed view that science is superior to common sense. Smith also explained the relationship between growth of private property and civil government: Men may live together in society with some tolerable degree of security, though