In his posthumously published treatise History of Economic Analysis (Oxford U Press, 1954; available here), Joseph Schumpeter made the following gratuitous and now oft-quoted claim: “… the fact is that The Wealth of Nations does not contain a single analytic idea, principle, or method that was entirely new in 1776.” (1954, p. 184, emphasis in the original) Alas, this legendary Austrian academic was wrong, for Chapter 2 of Smith’s Wealth of Nations (available here) contains three such original conjectures alone!

1. Man’s propensity to truck, barter, and trade. First off, Smith identifies the origins of the division of labour: “This division of labour, from which so many advantages are derived, is not originally the effect of any human wisdom, which foresees and intends that general opulence to which it gives occasion. It is the necessary, though very slow and gradual, consequence of a certain propensity in human nature … the propensity to truck, barter, and exchange one thing for another.” (WN, I.ii.1)
2. The butcher, the brewer, and the baker. Next, in what has to be one of the most memorable and most quoted sentences ever written in the English language, Smith explains how humans differ from non-human animals: “Nobody ever saw a dog make a fair and deliberate exchange of one bone for another with another dog. . . . But man has almost constant occasion for the help of his brethren, and it is in vain for him to expect it from their benevolence only. . . . It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantages.” (WN, I.ii.2)
3. The street porter and the philosopher. Last but not least, Smith propounds the basic natural equality of all men at birth: “The difference between the most dissimilar characters, between a philosopher and a common street porter, for example, seems to arise not so much from nature, as from habit, custom, and education. When they came into the world, and for the first six or eight years of their existence, they were perhaps, very much alike, and neither their parents nor playfellows could perceive any remarkable difference. About that age, or soon after, they come to be employed in very different occupations. The difference of talents comes then to be taken notice of, and widens by degrees, till at last the vanity of the philosopher is willing to acknowledge scarce any resemblance.” (WN, I.ii.4)