This excerpt:

> The increase in production can be attributed to three factors (1) an increase in dexterity amongst workers, (2) the time saved through division of labor, and (3) the invention of machines which can allow one man to do the work of multiple men.

Reminded me of an article that I'd read recently.  [Formal Education Doesn't Lift Worker Productivity. So What Does?](https://fee.org/articles/formal-education-doesnt-lift-worker-productivity-so-what-does/), by [Bryan Caplan](https://fee.org/people/bryan-caplan/).

It's interesting that 2 of Smith's factors show up in Caplan's article.  Specifically, Caplan says that "practice" and "management" explain the modern gains in productivity.  These align nicely with the increase of dexterity and the division of labor.

And even more interesting, commenters suggested that "tools" or "capital goods" should be added to Caplan's list.  This addition fits nicely with Smith's 3rd category, "machines."