"The man whose whole life is spent in performing a few simple operations, of which the effects, too, are perhaps always the same... generally becomes as stupid and ignorant as it is possible for a human creature to become."
This anxiety about the stupefying effects of cog-in-a-machine manufacturing sounds like a line from Karl Marx. It is, in fact, from Adam Smith's The Wealth Of Nations.
As the anniversary of Smith's death was last week, it seemed like a good moment to reflect on the Scottish philosopher's warning about the deadening effect of repetitive work. Smith knew that specialisation and the division of labour were not about to disappear, so he advocated publicly funded schools as a path to more fulfilling work and leisure.
The emergence of mass production lines made Smith's words seem prophetic; but many repetitive jobs have since been taken over by machines. So, has his warning about stultifying work been rendered obsolete?
The Wealth Of Nations is almost a quarter of a millennium old, and we should not expect every word to ring true today. But correctly read, Smith's anxiety continues to resonate - and not just for people with repetitive jobs, but knowledge workers too.
The modern knowledge worker - a programmer, a lawyer, a newspaper columnist - might appear inoculated from Smith's concern. We face not monotony but the temptations of endless variety, with the entire Internet just a click away. All too easily, though, we can be pulled into the soothing cycle of what slot-machine designers call a "ludic loop", repeating the same actions again and again. Check e-mail. Check Facebook. Check Instagram. Check Twitter. Check e-mail. Repeat.
Smith would not have dreamt of a smartphone, but what is a ludic loop but "performing a few simple operations, of which the effects, too, are perhaps always the same"?
Smith was concerned about jobs that provided no mental challenge: If problems or surprises never arose, then a worker "has no occasion to exert his understanding, or to exercise his invention, in... removing difficulties which never occur".
For the modern knowledge worker, the problem is not that the work lacks challenge, but that the challenge is easily ducked. This point is powerfully made by computer scientist Cal Newport in his book, Deep Work. Work that matters is often difficult. It can be absorbing in mid-flow and satisfying in retrospect, but it is headache-inducing and intimidating and full of false starts.
E-mail is easier. And reading Professor Newport's book, I realised that e-mail posed a double temptation: not only is it an instant release from a hard task, but it even seems like work. Being an e-mail ninja looks professional and seems professional -but all too often, it is displacement activity for the work that really matters.
A curious echo of Smith's warning comes in author Robert Twigger's new book, Micromastery. Twigger sings the praises of mastering one small skill at a time: not how to cook, but how to make the perfect omelette; not how to build a log cabin, but how to chop a log. There is much to be said for this. We go deep - as Prof Newport demands - but these sharp spikes of skill are satisfying, not too hard to acquire and a path to true expertise.
They also provide variety. "Simply growing up in the pre-modern period guaranteed a polymathic background," writes Twigger. To prosper in the pre-modern era required many different skills; a smart person would be able to see a problem from many angles. A craft-based, practical upbringing means creative thinking comes naturally. "It is only as we surge towards greater specialisation and mechanisation that we begin to talk about creativity and innovation."
I draw three lessons from all this. The first is that learning matters. Smith wanted schooling for all; Twigger urges us to keep schooling ourselves. Both are right.
The second is that serious work requires real effort, and it can be tempting to duck that effort. Having the freedom to avoid strenuous thinking is a privilege I am glad to have - but I am happier when I do not abuse that freedom.
The third lesson is that old-fashioned craft offered us something special. To Smith it was the challenge that came from solving unpredictable problems. To Twigger it is the variety of having to do many small things well. To Prof Newport, it is the flow that comes from deep immersion in a skill that requires mastery. Perhaps all three mean the same thing.
Smith realised that the coming industrial age threatened these special joys of work. The post-industrial age threatens them too, in a rather different way. Fortunately, we have choices.
"The understandings of the greater part of men are necessarily formed by their ordinary employments," wrote Smith. So whether at work or at play, let us take care that we employ ourselves wisely.
•Tim Harford is the author of Fifty Things That Made The Modern Economy.