Christopher Partridge provides a discussion of Michel Foucault’s use of psychoactive drugs and his subsequent reflection on the significance of the altered states they induce. Specifically, he analyzes Foucault’s comments on the hashish experiments conducted by the nineteenth-century psychiatrist Jacques-Joseph Moreau de Tours, who sought to induce the experience of “madness” in order to more fully understand his patients. What is significant, Partridge argues, is that, for Foucault, moments of madness can be moments of revelation, “the wisdom of fools.” Likewise, drug-induced altered states can be epiphanic. Novel insights are gained about the self and society, and, as such, they have the potential to be revolutionary. Partridge builds on this Foucauldian understanding of madness and intoxication by employing several ideas from Foucault’s subsequent work, notably, “technologies of the self,” “limit-experiences,” and “heterotopias.” The overall aim of the chapter is to posit a new way of understanding drug-induced altered states as politically significant moments of resistance.