The Sickness unto Death () is a book written by Danish philosopher Søren Kierkegaard in 1849 under the pseudonym Anti-Climacus. A work of Christian existentialism, the book is about Kierkegaard's concept of despair, which he equates with the Christian concept of sin, which he terms "the sin of despair". Walter Lowrie wrote that he saw the themes in The Sickness unto Death as a repetition of those in Kierkegaard’s earlier work, Fear and Trembling, and as being even more closely related to those in The Concept of Anxiety. Kierkegaard used two pseudonyms for opposite purposes: "Johannes Climacus" suggests that he is not a Christian, whereas "Anti-Climacus" suggests he is "an extraordinary Christian". Summary Anti-Climacus introduces the book with a reference to a phrase in the Gospel of John, 11:4: "This sickness is not unto death." The phrase occurs in John’s telling of the story of Lazarus, in which Jesus raises a man from the dead. However, Anti-Climacus raises the question: would not this statement still be true even if Jesus had not raised Lazarus from the dead? While the human conception of death is that it is the end of life, the Christian conception of death is that it is merely a stop along the path of eternal life, and thus nothing to be feared. Rather, it is the inability to die that is to be feared. The real "sickness unto death", according to Anti-Climacus, is not physical death but despair—a kind of spiritual death, which stems from not embracing one's self. According to Kierkegaard, an individual is "in despair" if he does not align himself with God or with God's plan for the self. In this way, he loses his self. Kierkegaard defines the self as the "relation's relating itself to itself in the relation," and defines the human experience as the tension between "the finite and the infinite", and between "the possible and the necessary". He writes that this tension is identifiable with the dialectical balancing act—the relationship—between these opposing features. Although humans are inherently reflective and self-conscious, to become a true "self" one must be conscious that the source and ground of this "self" is love, "the power that created it". When one either fails to understand the true nature of the self, or the true nature of the power that creates and sustains it, he says, one is in despair. There are three kinds of despair