The conception of the mirror stage. . .

1
In the opening paragraph of the essay Lacan makes reference to his presentation on the mirror stage at the (congress). The concept continues to be important for psychoanalysis, Lacan argues, because it accounts for characteristics of the central focus of psychoanalytic practice--the "I" which presents itself to the analyst (and, of course, the "I" of the analyst as well). In the Freudian model of the psyche, which Lacan, as a Freudian, takes as a point of departure for his ideas, the "ego" is not fully self-aware or in control of itself; the ego's perception of itself and of the world is shaped, in part, by the desires and fears arising from the id and from the injunctions imposed by the superego. Lacan's concept of the mirror stage tries to dramatize how the ego itself becomes divided.

At the outset, it is important to grasp two points.

• Lacan's version of psychoanalysis takes for granted that the human mind is not a unified whole, governed by reason--represented here by the reference to Descartes's Cogito--but that any self-knowledge is to some degree an illusion. Lacan frequently finds ways to contort Descartes's famous line "I think, therefore I am" (cogito ergo sum). He was also a harsh critic of American-style ego-psychology, which attempts to help the patient develop a strong ego, and which, in Lacan's view, compels the subject to conform to social conventions.
• The mirror stage is not only a passing phase of human psychological development but also a model for the relationship between the "I" and its image of itself. In a 1954 seminar, Lacan stresses the ongoing nature of the mirror stage (Seminar I 74).

2
The fact that human beings, unlike animals, recognize themselves in the reflected images of their bodies forms the basis for Lacan's speculations on the role of the image in the development of the human psyche. Lacan discusses this idea further in another 1954 seminar (Seminar I170). In the field of developmental psychology, one's awareness of one's own position within the physical world and the ability to imagine that position in relation to other physical objects is called "situational apperception".

3
An animal, even one as intelligent as a chimpanzee, will quickly lose interest in its reflection. A human infant, however, takes delight in relationship between her own movements and the movements of the image in the mirror. Long before the child can articulate the thought "that's me," her sense of being situated in the world (in Heidegger's terms, her sense of "being a being") develops when a image of her physical self establishes itself in her psyche in relation to the images of other elements of the world. This image doesn't necessarily have to be put in place by way of an experience with an actual mirror; other experiences--the attention of the mother to the child, for example--can give rise to the image of the self as a separate entity.