Søren Kierkegaard (1813-1855). Danish philosopher and theologian whose work — Either/Or, Fear and Trembling, The Sickness Unto Death, Concluding Unscientific Postscript — founded what the twentieth century would call existentialism. Kierkegaard's biographical record shows sustained depressive episodes, profound social isolation in Copenhagen despite (or because of) being one of the most distinctive figures in the city, an obsessive monotropic engagement with religious questions that produced thousands of pages of journal writing alongside the published works, and a cognitive style that operated through the construction of pseudonymous voices arguing different positions against each other (his books are often attributed to characters he invented, in dialogue with each other, rather than to himself). His cognitive signature is the discovery specialty operating in philosophy and theology at peak intensity, with the discomfort of social register that the specialty often carries, translated into a literary technique nobody else had used. The integration apparatus around him during his lifetime was thin — most of his work was self-published — and the international integration of his thought into modern philosophy did not happen until the twentieth century, sixty years after his death.