Freud wrote about death instincts in the plural, while the sexual instinct was always singular. Bergeret explores two hypotheses concerning this use of the plural. Freud may have meant to indicate that there are several forms of instincts leading to death or destruction. Or it may have been simply a generic plural connoting an imprecision in Freud's thought after 1920, as seen in the different successive definitions he gave of the concept. Freud's major discovery in the dynamic register was libido, and he never varied in his characterization of it after his letter to Fliess in June 1894. However, he sought various antagonists of libido, from life instincts to ego instincts, and finally the death instincts. This succession of different antagonists, always enunciated globally in the plural, reveals Freud's hesitation in determining the forces opposed to libido. Bergeret argues that his antagonism is not to