Early in Genesis we encounter the story of Cain (a farmer), who kills his brother, Abel (a shepherd), because he is jealous over God's (mysterious) unwillingness to accept his sacrifice (while accepting Abel's). In his The Philosophy of Hebrew Scripture (CUP, 2012), Yoram Hazony, reminds us that we are in addition to being a farmer, Cain also founds a city; cities are viewed negatively because of their tendency toward despotic-imperialism in the Hebrew Bible. [Full disclosure Hazony and I have co-authored a piece on Hume and Newton.] In Hazony's hands the Biblical (archetype) life of a shepherd (think also of Abraham, Moses, Jacob, David) stands for an anarchic "life of dissent and initiative" (108) away from the polity. While the life of the farmer (think of Noah, Isaac, and Joseph) stands for "pious submission, obeying in gratitude the custom that has been handed down, which alone provides bread so that man may live" (108). According to Hazony, The History of Israel (basically Genesis through Kings), favors the shepherding life, but as the story unfolds comes to recognize that anarchy is not self-sustaining. Hazony reads the Hebrew Bible as a search for a politics grounded in ethics--one that makes the state "limited in its aspirations" (153-4). (Some other time I'll say more about Hazony's handling of these issues.)
Implicit in this reconstruction of the Hebrew Bible is a kind of genealogy of civilization: first, in the Garden of Eden we are gatherers (maybe hunters, too); then, second, humanity splits in between mutually antagonistic shepherds and farmers, from which city-governments with an impulse toward territorial (and other) ambitions spring. As Hazoney notes (308 n. 26), Jean-Jacques Rousseau certainly read the Bible this way (see his posthumous Essay on the Origins of the Languages, written about the time of the second Discourse) and sides with the anarchic impulse of the "author of Genesis."
Now consider this prominent passage from Adam Smith:
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 which has in view no such extensive utility; the propensity to truck, barter, and exchange one thing for another. Adam Smith (Wealth of Nations, 1.2.1)
Consider this passage from David Hume:
The bulk of every state may be divided into husbandmen and manufacturers. The former are employed in the culture of the land; the latter work up the materials furnished by the former, into all the commodities which are necessary or ornamental to human life. As soon as men quit their savage state, where they live chiefly by hunting and fishing, they must fall into these two classes; though the arts of agriculture employ at first the most numerous part of the society.--David Hume (1752) "Of Commerce"
"Of Commerce" introduced readers to Hume's political economy and the quoted lines occur right after Hume's methodological introduction to the subject. Here Hume seems to equate the initial "savage" epoch with a kind of anarchy. Economically, people live by hunting and fishing without (much) division of labor. In political society, however, there is a division of labor between farmers and manufacturers. Hume intimates that in the course of time this second stage is transformed from being primarily agricultural to a society focused on making things, including (eventually) so-called luxury items. Hume also notes a third kind of activity, (foreign) commerce, which promotes this transformation, but does not assign it a seperate stage in history. (In fact, he thinks that trade can disappear from a large country without much loss.) Hume's genealogy is uninterested in shepherds.
One important difference between Hume and Smith is that for Smith the "savage" state need not be anarchical (there can be "kings," after all), although I will qualify this below. A second important difference is that Smith sharply distinguishes between four different stages or periods of society: a hunter-gathering period (savages); a second, shepherding period; a third, agricultural period, and a final commercial period. In principle, these stages are a successive, natural progression (Smith uses terminology of "advancement"), but, in practice, societies can deviate significantly and for very long periods from this natural development; for example, Book III of WN is an account of the "unnatural and retrograde order" of European development. (See here for evidence that Smith treats the stages as successive within a country and also capable of existing simultaneously among countries.) This terminology makes clear that for Smith, his four-stages theory is normatively loaded; the commercial state is, in principle, the best state. This is compatible with Smith's recognition that (a) there are trade-offs among the virtues and that "advancement" also means the loss of some splendid virtues (see especially work by Maureen Harkin, here and here)); (b) that, in practice, commercial states and the global commercial enterprises they support are capable of great injustices.
Now, we are in a position to reconsider Smith's focus on a propensity to exchange: the (fairly short) second chapter of WN repeats this propensity "to truck, barter, and exchange" (and its variants "to barter and exchange" and "by barter, and by purchase") like a mantra. In Smith's terminology "barter" is a species of commerce (see here, here, here). So, in the passage above (WN 1.2), Smith is claiming that by nature we are commercial types. That is to say, Smith's normative, stadial history is also in a way the realization of (or fulfillment) of mankind's nature. So, one of the causes of the wealth of nations is to be found inhuman nature (in context of proper institutional and moral framework; for more analysis on Smith's views on this propensity, see here.).
Smith recognizes that shepherding facilitates a life of leisure. Moreover, in Smith's account of the origin of government, the shepherding state is crucial because "some degree of that civil government" is introduced in it. (This is at odds with Smith's treatment of the African King and the European peasant at the start of WN, but it fits Smith's larger theory much better.) Even so, Smith is hostile toward shepherding, and when Smith reviewed Rousseau's second Discourse, he criticizes its positive treatment of shepherding as sublime fantasy. In WN Smith emphasizes that in shepherding societies conditions of great inequality and, thus, a relationship between "sovereign or chief" and subordinate "vassals or subjects" are generated (here). So, for Smith the inner logic of shepherding is not anarchic, but leads to a great deal of morally deplorable political dependence (rather than the more beneficial mutual, inter-dependent, independence of commercial societies).
In WN the Tartars or Arabs are the paradigmatic shepherding nations; Smith is conspicuously silent on the ancient Hebrews. Even so, we know that in his Lectures on Jurisprudence, he treats the "Children of Israel" as a "nation of shepherds" and equivalent to Tartars and Arabs of his time. (Elsewhere, Smith calls "the Jews ...originally a tribe of Arabs.") (Smith tried hard to ensure that all lecture notes were destroyed.) That is to say, for Smith the political ideal of the Hebrew Bible represents a backward state not to be emulated and not proper to the fulfilment of man's nature. As I learned from Ryan Hanley's important book on Smith, if we wish to understand Smith's theology, his views on religion, or design arguments, we need to stop obsessing about invisible hands. A good start would be to realize that Smith rejects the ideal of the shepherding life as unsuitable to man's nature and, thus, the idea that the "Good Shepherd" ought to be emulated.