The article focuses on the limit, the need and the desire. Starting from the recognition that the limit is consubstantial with the education. Indeed, the limit is the meta-rule that should inspire the individual rules. Then to analyze the desire on the basis of Lacan, Freud and other Authors. With the desire that is other than the pleasure and the enjoyment. And with the object of desire which is a ghost or an illusion. Lastly, with the need, which is the pedagogical response to the desire, defining a state of real urgency, physiologically connoted, of the subject. The same need, recognized and limited, which is the answer to a possible and practicable enjoyment, and, equally, to a well-posed and articulated question. A need updated, for quantity and quality, by the education. In view of the three main aims of the education: the freedom, the autonomy and the responsibility. And with the same pedagogy that does not legislate, but offers tools for their correct exercise. Thus, the educational relationship is able to educate desires, to submit them to the pleasure principle and, where if this fails, to bring everything back to the principle of reality, beacon and foundation of education.
Keywords: Limit, desire, principle of reality, need, education, pedagogy