Madness and Civilization: A History of Insanity in the Age of Reason

Foucault uses the term “Classical Period” to refer to an era more commonly called the “Enlightenment” by historians. Usually the word “Classical” refers to the period of antiquity between the 8th century BCE and the 5th century CE, so Foucault’s terminology may initially be confusing to those familiar with the conventions of historical writing. Since his analysis of the “Classical Period” constitutes the largest portion of the book, it is essential for readers to understand that he is referring to the 18th century CE when he uses this term.

Foucault defines “delirium” as the moment when an individual confuses their imagination with reality, clarifying that imagination on its own is not a form of “madness.” Delirium reveals that “madness” operates within the world of reason, since delirious individuals will often draw entirely logical conclusions from their delusions. Foucault presents the example of a man who believed he was made of glass, who therefore “concludes that he [was] fragile,” and should avoid movement and hard objects (102). 

Foucault identifies two forms of delirium in Enlightenment thought: the first is a symptom of several forms of “madness,” but the second is a broader delirious system of thought (Foucault uses the word “discourse”) that is present in everybody.