[The collection from which this excerpt is taken was originally published in 1964 under the title Essais critiques.]

[In Folie et déraison: Histoire de la folie à l'âge classique, Foucault] has not written the history of madness, as he says, in a style of positivity: from the start he has refused to consider madness as a nosographic reality which has always existed and to which the scientific approach has merely varied from century to century. Indeed Foucault never defines madness; madness is not the object of knowledge, whose history must be rediscovered; one might say instead that madness is nothing but this knowledge itself: madness is not a disease, it is a variable and perhaps heterogeneous meaning, according to the period; Foucault never treats madness except as a functional reality: for him it is the pure function of a couple formed by reason and unreason, observer and observed...