[I. A mirror to reflect]

To explain the specular permutation of the right and the left an adult subject has recourse continually to expression--image. An elementary optical study demonstrates that explanation leads to metamorphose the flat-mirror in a lentil. In fact the operation truth-fully realized by the mirror is an antero-posterior rotation of subject causing necessary but secondary a couple right left rotation. The unvariance of this behaviour and these false answers authorizes to represent the mirror like an operator motiving the subject's identity without we understand the utmost reason. A second memory will thy to give an explanation of that fact to start from a symbiosis between the breuero-freudian theories and the piagetian concept.