To characterize the heightening that occurs between sin and despair over sin, one could say that the former breaks with the good and the latter with repentance. Despair over sin is an attempt to keep going by sinking even deeper. As the balloonist climbs by casting off weights, the despairer sinks by more and more determinedly casting off all good (for the weight of the good is uplifting); he sinks though in the belief, to be sure, that he is rising – and indeed he does become lighter. Sin itself is the struggle of despair, but when energy is exhausted there has to be a new intensification, a new demonic withdrawal into oneself, and that is despair over sin. It is a step forward, a heightening of the demonic, and of course a deeper absorption in sin. It is an attempt to give to sin some backbone and engagement as a power by its being now for ever decided to hear nothing of repentance, nothing of grace. And yet despair over sin is conscious precisely of its own emptiness, of its having nothing whatever to live on, not even a self-image. The line Shakespeare gives to Macbeth (Act II, Scene I) is a master-stroke of psychology: ‘For from this instant [having murdered the king-and now despairing over his sin] there’s nothing serious in mortality: all is but toys: renown and grace is dead.’ What is masterly is the double stroke in the final words (renown and grace). Through the sin, in other words, through despairing over the sin, he has lost all relation to grace – and also to himself. His selfish self culminates in ambition. For now he has become king and yet, in despairing over his sin and of the reality of repentance of and of grace, he has at the same time lost himself; he cannot keep it up, even for himself, and he is no closer to enjoying his own self in his ambition than he is to grasping grace.
Søren Kierkegaard Guest Series: The Sickness unto Death (1849)