The figure of the masturbator appears at the end of the eighteenth century with a number of specific characteristics distinct from those of both the monster and the individual to be corrected. The first is that the masturbator is not at all an exceptional figure in eighteenth-century thought, knowledge, and pedagogical techniques; he is, rather, a frequently encountered individual. He seems to be an almost universal individual. Now this absolutely universal individual, or rather, the practice of masturbation that is recognized as being universal is, at the same time, said to be an unknown or ignored practice that no one has spoken about, that no one knows and whose secret is never revealed. Masturbation is the universal secret shared by everyone but disclosed to no one.
In the lectures comprising Abnormal, Foucault shows how and why defining ‘abnormality’ and ‘normality’ were prerogatives of power in the nineteenth century, shaping the institutions—from the prison system to the family—meant to deal in particular with ‘monstrosity’.