The term is used in both Freudian psychoanalysis and Jungian analytic psychology to describe organized sets of ideas and memories that are largely unconscious but have enormous affective power.
Complex and Imago
before 1950, where it is closely related to the image.
the complex is a whole constellation of interacting imagos; it is the internalisation of the subject's earliest social structures (i.e. the relationships between the various actors in his family environment).
A complex involves multiple identifications with all the interacting imagos, and thus provides a script according to which the subject is led "to play out, as the sole actor, the drama of conflicts' between the members of his family."
In his pre-war work, Lacan argues that it is because human psychology is based on the complexes, which are entirely cultural products, rather than on natural instincts, that human behaviour cannot be explained by reference to biological givens.
Nevertheless, while drawing this explicit contrast between complexes and instincts, Lacan also recognises that complexes may be compared to instincts in that they make up for the instinctual inadequacy (insuffisance vitale) of the human infant, and argues that the complexes are propped on biological functions such as weaning.
Taking up the idea of a "trauma of weaning," first developed by René Laforgue in the 1920s, Lacan argues that no matter how late weaning occurs, it is always perceived by the infant as coming too early.
Whether traumatic or not, weaning leaves in the human psyche a permanent trace of the biological relation which it interrupts. This life crisis is in effect accompanied by a psychical crisis, without doubt the first whose solution has a dialectical structure.