Not surprisingly, one of the more commonly accepted explanations of Mill’s breakdown at the age of 20, is that it was caused by cumulative mental exhaustion. But Mill himself understood it differently. In his autobiography, he wrote:

I was in a dull state of nerves, such as everybody is occasionally liable to: unsusceptible to enjoyment or pleasurable excitement; one of those moods when what is pleasure at other times, becomes insipid or indifferent… In this frame of mind it occurred to me to put the question directly to myself, ‘Suppose that all your objects in life were realized; that all the changes in institutions and opinions which you are looking forward to, could be completely effected at this very instant: would this be a great joy and happiness to you?’ And an irrepressible self-consciousness distinctly answered, ‘No!’ At this my heart sank within me: the whole foundation on which my life was constructed fell down. All my happiness was to have been found in the continual pursuit of this end. The end had ceased to charm, and how could there ever again be any interest in the means? I seemed to have nothing left to live for.

In the wake of this episode, Mill slipped into a six-month-long depression.

There is something comical about Mill’s self-implosion; it’s as if he had spent years looking forward to a sailing trip only to suddenly realize, upon embarkation, that he hated boats.

It is also strangely relatable. We have all lost faith in a deeply held project at one time or another. And, politically, we are in an age of upheaval; faith in old ideals seems to be dying out, creating a vacuum. Perhaps we can learn something about ourselves, and our political moment, by peering into Mill’s own crisis of faith.

Why on earth wouldn’t Mill want to achieve his life goals?

It wasn’t because he thought he had the wrong goals. Mill never did abandon utilitarianism, though he later modified Bentham’s doctrine in subtle ways. Instead, Mill tells us that his crisis was born in a concern about whether happiness is really possible in the perfect world he sought to achieve — a world without struggle:

[T]he question was, whether, if the reformers of society and government could succeed in their objects, and every person in the community were free and in a state of physical comfort, the pleasures of life, being no longer kept up by struggle and privation, would cease to be pleasures.

Mill is not at all clear about his line of thought here. But we can speculate. One possibility is that he is worried that, if we ever were to achieve an ideal social world, we would quickly take it for granted, or become “spoiled.” It’s a familiar tale: the child that always gets what he or she wants ends up forever unsatisfied and always wanting more (psychologists call this the hedonic treadmill). And perhaps Mill thought the same is true for adults — that facing a degree of “struggle and privation” in life is essential to happiness, because it provides us with a vivid reminder of how lucky we are when we have it good.

Or was Mill concerned that, in a perfect world, with nothing more to strive for, we might simply grow bored? As the 19th century German philosopher Arthur Schopenhauer once upliftingly put it, “life swings back and forth like a pendulum between pain and boredom.” When we are not consumed by the desire to achieve something (food, shelter, companionship, wealth, career, status, social reform, etc.), we are tortured by boredom.