This chapter reviews the Freudian concept of negation. Probably the considerations that Sigmund Freud gives to the object in his model are those that allow a glimpse of the problems resulting from non-neurotic pathologies. Melanie Klein was perhaps the first to attribute to negation the character of a very early mechanism that preceded repression. The proposed interpretation subsequently analyses the speculative model created by Freud in order to explain the psychological origin of the function of negation, pointing out the importance that is attributed in it both to the representation—trace of the initial statement—as well as to the loss of the object of satisfaction. "Negation", in particular, offers itself for continuing reflection, as if what it can give to the attentive analyst could never be exhausted. Negation allows thought a first level of independence from the effects of repression, and it is the type of relation that the neurotic and normal subject has with the unconscious.