The odds didn't look good for the new film version of The Great Gatsby this weekend, I thought, as I donned my plastic 3-D glasses and entered the dark theater. I wasn't expecting to like the movie much at all.

I don't love glitzy Hollywood spectacle, though I was willing to give the much-hyped new version of F. Scott Fitzgerald's great novel a chance because it was directed by Baz Lurhmann, a commanding figure in popular experimental cinema with an almost Warholian taste for edgy spectacle. I'd loved his Moulin Rouge, a wicked send-up of chic Paris in the era of Toulouse-Lautrec and absinthe.

If any big director was going to ruin Great Gatsby, I thought, it might as well be Luhrmann, who had apparently hired Jay-Z, Beyonce, Q-Tip, Lana Del Rey and Will.i.am for an anachronistic soundtrack (Moulin Rouge, similarly, gave us Nirvana's "Smells Like Teen Spirit" in 19th Century France, and made it work.)

But my hopes weren't very high as I entered the theater and put my Gatsby Glasses on. The idea of a 3-D version of a literary love story seemed ridiculous. I was also unhappy with the casting of the histrionic Leonardo DiCaprio in the title role. I'd watched this overrated actor bluster through several promising literary movies already: Basketball Diaries, Total Eclipse, Gangs of New York, Revolutionary Road. I knew he only had six facial expressions, and I was sick of them all. I was ready to start hating the movie, as the lights in the theater went out.

The great Danish philosopher Soren Kierkegaard never married, but he anguished for years over the existential personal puzzle of love and marriage. He transformed the question into a revolutionary book, Either-Or, published anonymously as Enten-Eller in 1943. This debut work immediately captivated readers, and would turn out to be not only his breakthrough work as a philosopher but also the most successful book he would ever write. Originally published in two volumes, it pretended to be a miscellaneous set of documents found in a desk, loosely edited by a nonexistent person named Victor Eremita.

The documents present a literal "either/or" representing two attitudes: a young Copenhagen fop who writes essays and speeches expressing his dread of the idea of marriage, and the young man's uncle urging his nephew to take the leap. The book also includes texts collected by these men: a "diary of a seducer", a sermon by a country priest. Later commentators have characterized the first figure in Either-Or as a representative the lifestyle of the "Aesthetic Man", and the second figure as the representative "Ethical Man". In this set of documents, neither side wins the argument clearly, suggesting that neither the aesthetic nor the ethical attitude towards life can ever exclude the other. There may be a third implicit voice presented in Either-Or, the voice of the philosopher who apprehends both sides of the question and realizes the impossibility of ever solving the puzzle. This voice has been characterized as that of the "Existential Man", and can be presumed to represent Soren Kierkegaard's own attitude as he fabricated the eternal opposition represented by this book.

What do you buy a morose Danish philosopher who invented Existentialism for his 200th birthday?

It doesn't really matter anymore, since Soren Aabye Kierkegaard is dead. He died at the young age of 42, already at this time a mostly broken man, an obsessive writer, a lonely bachelor, and a frequent subject of popular ridicule. Like Henry David Thoreau, Herman Melville, Franz Kafka and F. Scott Fitzgerald (with all of whom he shares some sensibility), he died at a low point of literary success, without much reason to expect that later generations would rediscover his work and call him a genius.

But I believe Soren Kierkegaard died a happy man, because he was that rare philosopher who found answers to the hardest questions he asked, answers that satisfied him completely. The questions were of religion, and of how to live a good life, and his answer involved the "leap of faith" or "leap to faith" (a phrase he invented). Kierkegaard was a devoted Christian, but he defied the philosophical norms of his age by expressly refusing to try to justify his belief with reason or logic. The power of religious faith, he pronounced, was in believing without reason or logic.

His belief in Christianity made him a great religious writer. What made him a great Existential writer was the implicit principle that underlies his argument for religious faith: the principle that we human beings regularly think, live and make decisions without reason or logic.

This was as much a "eureka" moment for Western philosophy as Rene Descartes's cogito ergo sum two centuries before. Though Kierkegaard had to struggle to explain his ideas to his bewildered Danish and European intellectual peers during his life, his idea of religion as a leap to faith would spring incredible gardens of original modernist thought: inheritors of Kierkegaard include Fyodor Dostoevsky, Friedrich Nietzsche, William James, Paul Tillich, Ludwig Wittgenstein, Jean-Paul Sartre and many more.