What is The Sickness Unto Death about?

The Sickness Unto Death, published in 1849 under the pseudonym Anti-Climacus, is Kierkegaard's most rigorous psychological and theological analysis of despair — which he defines not as an emotion but as a structural failure of selfhood. The title comes from the Gospel of John (the story of Lazarus), but Kierkegaard reinterprets the sickness unto death as despair: a condition from which there is no exit except through faith, and which can be fatal to the spirit even while the body survives.

The opening definition is one of the most demanding in the entire philosophical tradition: a human being is a synthesis of the infinite and the finite, the temporal and the eternal, freedom and necessity. The self is the relationship between these poles — not one of the poles but the relational activity itself. Despair arises when this relationship fails: when the self either loses itself in the finite (failing to become itself) or exhausts itself in abstraction from the finite (also failing to become itself). Both failures are forms of despair, and the person in either form is not at rest in the relationship that they are.

Kierkegaard identifies three intensifying forms of despair. The first is unconscious — the person does not even know they are in despair, which Kierkegaard considers the most common and most dangerous form. The second is conscious despair about something temporal — the refusal to accept a loss or failure. The third is defiance: the most intense form, in which the self, conscious of despair, refuses to be itself as it is constituted and instead wills to be itself on its own terms, independent of the power that establishes it. This last form is closest to sin in Kierkegaard's theological framework.

The second part of the book is explicitly theological: sin is defined as despair in the face of what one knows about God. The only exit from despair is faith — the condition in which the self rests transparently in the power that constitutes it. This is not intellectual assent to doctrine but a total orientation of the self, a rest in relation to God that ends the perpetual flight and misrelation. Kierkegaard does not claim this is easy, common, or comfortable, but insists it is the only genuine resolution of the human condition.