Fyodor Dostoevsky’s underground man lives in a subterranean world of his own creation. One of his primary complaints is of his own physical illness or misery, but the corollary to this complaint is that he is not truly ill. The actual nature of his anxiety seems to be existential malaise. Rather than suffer from any disease, he is not at ease:
[A] great deal of consciousness, every sort of consciousness, in fact, is a disease.
His obsession with illness leads him to contemplate what constitutes health. This man argues that no one can actually be healthy because that would require them to accept all the conditions of mortality, or to acquiesce to the pain and sufferings of others. Thus, in first claiming and then rejecting his own suffering, the underground man establishing empathy with other human beings—a necessary condition of being human.