Kierkgaard's short, yet influential, work The Sickness Unto Death appeared on July 30, 1849. The book was written a full year earlier in the spring of 1848. Kierkegaard kept the manuscript for several months along with a number of other works that he had recently completed before he decided to have it printed. One of the reasons for the delay was that he was contemplating publishing it as a part of a larger work that included parts of Practice in Christianity, The Point of View, Armed Neutrality, and Two Ethical-Religious Essays. This is clear from his journals, where he writes: “My intention was to publish all the completed manuscripts in one volume, all under my name – and then to make a clean break.” In the end, of course, the works were published individually, some signed and some pseudonymous.

With regard to its content, The Sickness unto Death can be seen as a kind of Christian psychology or anthropology. Part One is divided into three sections labeled simply A, B, and C. In the first section Kierkegaard's pseudonym Anti-Climacus analyzes the notion of despair, which, he argues, is the sickness unto death. In Section B, he makes the case that this sickness is more widespread than is generally recognized. In Section C, “The Forms of the Sickness,” he gives a taxonomy of the various forms of despair in accordance first with the categories of finitude/infinitude and possibility/necessity and then later with the levels of consciousness.