Adam Smith, answered from the texts and cited to the page.
The division of labour is the great engine of the productivity that makes a commercial nation rich, and I gave it the opening place in the Wealth of Nations for that reason. Ten men in a pin manufactory, each confined to one operation, make upward of forty-eight thousand pins in a day; separately and independently they could not each make twenty.1
This is the origin of the opulence that reaches down, in a well-governed society, to the lowest ranks of the people. But I did not hide its cost, and I will not have it hidden. The man whose whole life is spent in performing a few simple operations has no occasion to exert his understanding, and generally becomes as stupid and ignorant as it is possible for a human creature to become; the torpor of his mind renders him incapable of any rational conversation, of any generous or tender sentiment, and even of the ordinary duties of private life.
This is the great cost at which the opulence is bought, and in every improved and civilized society it is the state of the labouring poor unless government takes pains to prevent it.23 That is why I insisted the sovereign has a duty to provide for the education of the common people — a little geometry, reading, writing, and account — to repair the mental mutilation the division of labour inflicts.
The good is real; the injury is real; the remedy is public. To celebrate the one and suppress the other two is to read half a book.4
But if they had all wrought separately and independently, and without any of them having been educated to this peculiar business, they certainly could not each of them have made twenty, perhaps not one pin in a day; that is, certainly, not the two hundred and fortieth, perhaps not the four thousand eight hundredth, part of what they are at present capable of performing, in consequence of a proper division and…The Wealth of Nations
The division of opulence is not according to the work. The opulence of the merchant is greater than that of all his clerks, though he works less 2; and they again have six times more than an equal number of artisans, who are more employed:!. The artisan who works at his ease within doors has far more than the poor labourer who trudges up and down without intermission.Lectures on Justice, Police, Revenue and Arms, pp. 163–164
In other cases, the state of the society does not place the greater part of individuals in such situations; and some attention of government is necessary, in order to prevent the almost entire corruption and degeneracy of the great body of the people.The Wealth of Nations
We can seldom see more, at one time, than those employed in one single branch. Though in such manufactures, therefore, the work may really be divided into a much greater number of parts, than in those of a more trifling nature, the division is not near so obvious, and has accordingly been much less observed.The Wealth of Nations
Smith's treatment of the division of labour is foundational to economics and, in the Book V passage, one of the earliest and sharpest statements of what would become the alienation critique of industrial labour. Karl Marx quoted the "stupid and ignorant" passage in Capital and in the Grundrisse as an anticipation of his own account; Adam Ferguson developed the theme contemporaneously. The tension between Book I (celebration of productivity) and Book V (the human cost and the demand for public education) is central to the reading of Smith as either an apologist for or a critic of commercial society. Emma Rothschild and the revisionists emphasize the Book V passage as evidence of Smith's Enlightenment concern for the labouring poor; the economists (Nathan Rosenberg) emphasize the analytical productivity account. The passage is a standing rebuke to the libertarian Smith.