Anxiety may be compared with dizziness. He whose eye happens to look down the yawning abyss becomes dizzy. But what is the reason for this? It is just as much in his own eye as in the abyss, for suppose he had not looked down. Hence, anxiety is the dizziness of freedom, which emerges when the spirit wants to posit the synthesis and freedom looks down into its own possibility, laying hold of finiteness to support itself. Freedom succumbs to dizziness. Further than this, psychology cannot and will not go. In that very moment everything is changed, and freedom, when it again rises, sees that it is guilty. Between these two moments lies the leap, which no science has explained and which no science can explain. He who becomes guilty in anxiety becomes as ambiguously guilty as it is possible to become.
Kierkegaard on anxiety.