The constitution of madness as a mental illness, at the end of the eighteenth century, affords the evidence of a broken dialogue, posits the separation as already effected, and thrusts into oblivion all those stammered, imperfect words without fixed syntax in which the exchange between madness and reason was made. The language of psychiatry, which is a monologue of reason about madness, has been established only on the basis of such a silence.