It seems that every advertising pole in downtown Toronto is slathered with placards advertising Allen Bates’ performance of Ibsen’s Master Builder. And so they should be. It is not often, even in this cosmopolitan city, that we get the opportunity to see a great actor in a classic play.

Especially because the Master Builder is something even more interesting than a classic. Written in 1892, it is a perfectly preserved expression of the worldview of the 1890s, the decade in which our bloodsoaked modern world was born.

The 1890s was a decade of enormous intellectual and literary achievement, and almost all of that achievement was devoted to a single theme — the need to shake off the dusty old restraints and inhibitions of the past. Halfway through the Master Builder, the young girl who loves the lead character, architect Halvard Solness, expresses her great wish: “If I had a really strong conscience, brimming with health — so you could dare what you most wanted.”

Be strong; be healthy; dare what you want. Accept no limits on your desires. It is the theme of an age — their age, and ours. It was the theme of the most influential philosopher of the 1890s, Friedrich Nietzsche, who condemned all conventional morality and called instead for each and every human being to construct his own code of values. It was the theme of the revolutionary socialists of the decade who celebrated violence as an end in itself.

It was the theme of the twittery artists and writers of the Bloomsbury clique; the theme of the young Freud; the theme, in a curious way, of the foreign policies of the great imperial powers of Europe in those days. What we now think of as the great project of the 1960s — liberating human passions from all constraint — was a project in fact begun 70 years before.

Listening to Ibsen’s mighty plea for the emancipation of all desires reminded me of a little boy opening a tiger’s cage in order to pet the beast on the nose. A kindly man and a good Victorian, could Ibsen have had any conception of the enormous evil that lurked in the tiger’s cage?

We, in the libido-soaked 1990s, always associate the word “desire” with sex. But Ibsen’s contemporaries understood that human beings entertained many desires, and they were prepared to let them all loose — including the desire that Sigmund Freud in the end considered the most powerful of all, the desire for violence and death. “War is a biological necessity of the first importance,” a respectable German writer contended in 1911. He was merely echoing Nietzsche: “Ye say a good cause will hallow even war? I say unto you: a good war halloweth every cause.”

A 100 years later, as we emerge from the nightmare of the 20th century, we can only shake our heads in dismay at the lack of foresight of the early moderns.

Or can we? I wonder whether we have learned our lesson yet. As long ago as 1938, John Maynard Keynes diagnosed the errors of the 1890s, errors to which he and his Cambridge University intellectual circle had subscribed in their youth. In his lecture, My Early Beliefs, Keynes confessed that those beliefs had been founded upon a “disastrously mistaken” view of human nature.

In the 1890s, he said, he and his friends had convinced themselves that human beings were sufficiently rational to be “released from … inflexible rules of conduct, and left, from now onwards, to their own … reliable intuitions of the good.” He now realized that they had been wrong. They had failed to understand that “civilization was a thin and precarious crust erected by the personality and will of the few, and only maintained by rules and conventions skillfully put across and guilefully preserved.”

Keynes’ midlife defence of conventional morality was excessively cynical. Well, he was a cynical man. But he was right. Ibsen, like all prophets of liberation from convention in his time and ever since, was wrong; entirely, dangerously, murderously wrong.