Finding someone who embodies a particular era is not the same as selecting Time magazine's Person of the Year.

Time's year-end notable can be an accomplished individual or, like the choice for 2011, The Protestor, a part of a heroic movement.

But a truly representative personality can also be more checkered, full of paradox and unresolved longings.

As well, he or she can be well known in one era and almost totally unknown in another, thrown into the "dustbin of history," along with their enthusiasms.

Take the 20th century's obsession with communism. From this passion many figures emerged, now totally marginal and forgotten.

Lost in our current obsessions, we forget that revolutionary socialism held a lock on the minds of millions of fervent people, significant and ordinary.

One of the more significant was Arthur Koestler, a 20th century journalist, novelist and public figure who was once touted for a Nobel Prize in literature.

His life leaps from the detailed pages of Michael Scammell's biography, Koestler: The Literary and Political Odyssey of a Twentieth Century Skeptic. (You can hear Scammell tell his story on a recent broadcast of CBC Radio's Ideas.)

Arthur Koestler. (CBC)

The book's subtitle can be misleading. Arthur Koestler was not really a skeptic.

A skeptic remains disinterested, somewhat above the fray. But Koestler was a "true believer" in not just communism but in a series of passions that swept the era.

Throughout his career, he dove into one obsessive cause after another, from communism to science to the paranormal.

As well, he seemed to show up almost everywhere, like a real-life Forrest Gump. If history was happening, Koestler was likely there.

A witness to his times

Born in Budapest in 1905 and educated in Austria, Koestler developed into an ardent witness to his times.

In the 1920s, he went to Palestine, hoping to see a fledgling Jewish socialist state in the Middle East; then he moved to Germany to become a stylish, much celebrated journalist, and revelled in the attention.

He could be seen around town, dashing and well dressed, driving a red sports car with a cigarette dangling from his lips. He hitched aboard the Graf Zeppelin airship on its famous Polar flight, the moon shot of its day.

By then, of course, the Depression had seized hold of Europe and millions were unemployed. Capitalism appeared to have collapsed.

The era was exciting, sure enough, even glamorous, but so many seemed utterly lost.

For them, Soviet Communism offered a way out of the morass. "I have seen the future and it works," the American writer Lincoln Steffens said at the time of the beginnings of the Soviet experiment.

So in 1931, in Berlin, Koestler became a communist. Later, he toured the Soviet Union.

The thumb of the powerful

Like almost everyone who visited the new workers' paradise in those heady days, he chose to not see the evidence (admittedly not fully on display) of the starvation and murder in the Ukraine, and the beginnings of a monstrous, Stalinist repression.

In the mid-1930s Koestler went on to cover the Spanish Civil War, where the ideological struggles of the time converged -- Franco's Fascists against the socialist, anarchist and communist partisans.

Thrown in prison, Koestler heard jailers unlock cell doors and accompany those prisoners about to be executed. Waiting in his cell, in his filthy, once fashionable suit, he fully expected to die.

Prison helped to teach him about experience of utter powerlessness. As a prisoner, he observed himself as he tried to please his guards and interrogators.

It drove home the point of how grovelling and embarrassing one could be under the thumb of the powerful.

Still, Koestler came to appreciate the small kindnesses that were sometimes offered: a cigarette, a few humane words from a guard.

Yet he was no ordinary prisoner. As a celebrity journalist, he was released in exchange for one of Franco's favorite pilots who had been shot down and captured.

Darkness at noon

So why should we consider Koestler, who died in London in 1983, an iconic or representative figure of his time?

The answer lies not only in his passions, but in his disappointments, which he was courageous enough to face, while many others, hungry for a better world, could not.

"Nothing is more sad than the death of an illusion," Koestler said at one point, the illusion being communism.

In 1940, his best known work, Darkness at Noon was published (it is still in print).

In the novel, an old Russian Bolshevik, Rubashov, is imprisoned in the late 1930s during one of Stalin's show trials. The tragedy is not only that the revolution had betrayed and murdered millions. But that Rubashov continued to deceive himself and willingly goes to his execution for the good of the party.

Pilgrim

One of Koestler's great themes was this struggle between means and ends. How many eggs do you break to make an omelet? How many innocents need to be sacrificed in the cause of creating a better world?

Some illusions die hard. A Georgian man proudly shows off his mementoes of Stalin in a demonstration in 2010. (Associated Press)

Is one too many? A few? What's the formula?

This is still a crying question for our newest century. Think of the wars that have been waged, some for a supposedly good reason.

Koestler went from being a communist to becoming a vocal anti-communist (editing The God that Failed, another well known title).

Moreover, behind his tumultuous journey was another deep, contemporary echo. His wasn't only a political search, but a religious one as well.

Koestler moved from politics to science, then sought to open the "doors of perception" by experimenting with LSD with Timothy Leary and writing about parapsychology.

With his restless soul — and his turbulent and often unpleasant personality, which displayed a singular ugliness in his relations with women — he was very much the 20th-century pilgrim.

A secular Jew all his life, he hungered for meaning, even for transcendence and, in his later years, he even flirted with becoming a Catholic.

In the end, his message is a sober one: be wary of your illusions — even your best hopes and dreams can turn into fanaticism, the shadow side of one's deepest longings.