Lacan places a special emphasis on the role of the image, defining identification as “the transformation that takes place in the subject when he assumes an iamge” (E, 2). To “assume” an image is to recognize oneself in the image, and to appropriate the iamge as oneself.
Imaginary identification is the mechanism by which the ego is created in the mirror stage; it belongs absolutely to the imaginary order. When the human infant sees its reflection in the mirror, it identifies with that image. The constitution of the ego by identification with something which is outside the subject is what “structures the subject as a rival with himself” (E, 22) and thus involves aggressivity and alienation. The mirror stage constitutes the ‘primary identification,’ and gives birth to the ideal ego.