Human nature, John Stuart Mill tells us, is not a machine cast in an iron mould, aimed to perform predetermined tasks carefully designed by some Darwinian blueprint. Rather, it is a tree, growing on all its sides, developing, according to its own inner forces – the very forces that make it a living thing.

The constant tension between the need for tradition in society and the need for individual expression is inescapable. In a time when the ‘tyranny of the majority’ is as much a cultural phenomena as it is a political one, individuality has never been more a valuable currency.

In On Liberty, a philosophical treatise published in 1859, John Stuart Mill presents perhaps the fiercest and most eloquent defence of individuality. For Mill, carving out our paths and realising our own life projects requires the liberation of the individual from the shackles of tradition. As Mill declares, “Over himself, over his own body and mind, the individual is sovereign.”

Of the great English philosophers of the 19th century, none are more eminent than John Stuart Mill. A precocious youth, Mill displayed a supreme intellectual capacity as early as the age of eight, already fluent in both Greek and Latin. Under the careful tutelage of his father, James Mill, and his other great philosophical contemporary, Jeremy Bentham.

By the ripe old age of twelve, Mill had reportedly mastered philosophy, political economy, mathematics and historical literature. (Maybe Thomas Jefferson was wrong after all: perhaps not all men are created equal.)

Yet, like all great stories worth telling, there soon was a crisis.

In 1826, at the age of 20, Mill experienced a mental breakdown. Ever since, the causes have been the subject of much speculation: his overly demanding father, his emotionless ice cold childhood, and the unrelenting burden of expectation remain prime suspects.

Over the next four years, battling constant bouts of depression and anxiety, Mill’s recovery was gradual at best. In the wilderness of his despair, he seemed unable to find any light at the end of the tunnel.

That was until 1830 when he met Harriet Taylor, his confidant, his friend, and his eventual wife. To Mill, Taylor was the beginning and end of his whole life. “To her outer circle”, he writes, “she was a beauty and a wit, with an air of natural distinction, felt by all who approached her: to the inner, a woman of deep and strong feeling, of penetrating and intuitive intelligence, and of an eminently meditative and poetic nature.” This was no ordinary woman.

There was but one small problem: she was married.

Thankfully, this would not stop their friendship. Over the next two decades, they formed an inseparable, intense relationship that while strictly platonic, remained deeply scandalous. Simply put, there was nothing actually improper with their friendship while she was married to her first husband. However, that did not stop their relationship being seen by mainstream society as an immoral violation of social custom. The gossip and rumour escalated to the point where Taylor felt that she a victim of tradition – one where a woman is disgraced if she dares befriend a man who is not her husband.

When Taylor’s husband died in 1849, the two married without support from friends or society’s approval. Such was the burden of cultural norms. For the remainder of their marriage, which lasted until Taylor’s death in 1858, they retreated from British society. Together, they began work on a new treatise inspired by their indignance towards society’s mistreatment of their friendship and eventual love, and they titled it On Liberty.

Its conception rested on a very simple and personal realisation: that if all they did were obey the conventions and traditions set out by society on how they ought to live their lives, they would have never fallen in love.

The argument for free expression (both in thought and in character) in On Liberty is two-pronged: on the one hand, it suggests that it is best for individuals when they are given the freedom to pursue their own path in life; on the other hand, it is best for society as well.

Together, their wisdom is incisive: “In proportion to the development of his individuality, each person becomes more valuable to himself, and is, therefore, capable of being more valuable to others… without them, human life would become a stagnant pool.”

They continue, “Human beings are not like sheep; and even sheep are not indistinguishably alike. A man cannot get a coat to fit him unless they are either made to his measure, or he has a whole warehouse full to choose from.”

Of all the forms of tyranny incompatible with freedom, Mill and Taylor identified social tyranny, or the ‘despotism of custom’, as the foremost affront to human flourishing. Much of On Liberty involves a vigorous attack on civil society for what he and Taylor saw as a fostering of a “spirit of conformity” that suppressed an individual’s capacity for self-determination.

In other words, perhaps the greatest danger mass society poses to its constituents is in the form of implicit and explicit demands of self-repression and conformism, all of which are made under the fatuous assumption that the only acceptable ways to live your life are those that are in line with mainstream societal convention. Never seek shelter in the illusory comfort of tradition.

When John Stuart Mill died in 1873 at the age of 66, he had an immeasurable influence on philosophical logic and political economy. Yet his greatest contribution was his defence of basic civil liberties, for his rallying cry against the culling of the individual in the face of tradition and custom. For that, we must thank Harriet Taylor.