And now, if we try to assign a value, in and of itself, outside its relations to the dream and with error, to classical unreason, we must understand it not as reason diseased, or as reason lost or alienated, but quite simply as reason dazzled.

Unreason is an important presence in Madness and Civilization, but this is the only real definition that of it Foucault offers. Unreason in the classical period is not exactly the opposite of rational thought, but has a complicated relationship to reason. The madman, who is seen as a representative of unreason, is in many ways like a blind man. He sees the same "“light” of reason as the sane man, but is confused and dazzled by it. Foucault is clear that unreason is not a disease or deformation of reason, but merely a different attitude towards it. Understanding how this attitude develops, or how reason becomes “dazzled” is no simple matter, as Foucault demonstrates.