In nursery schools, teachers are sometimes confronted with children presenting a large range of behavioural incongruities. Isolation, agitation, emotional discharges are not only the manifestations of some developmental differences; they are also a way to show the child’s singularity. These manifestations do not have a communicational value, so teachers are often destabilized. Either they will assimilate these symptoms to mental retardation and wait for the maturational process to go on, or they will send the child to a developmental specialist who will diagnose autism. Kanner defines autism by three key-symptoms: extreme isolation, language disorders, an urgent need for the environment not to change and stereotypical movements. Despite the variability encountered in different cases, these three signs are recognized as the basis of autism. Nowadays, research on autism is an open field and several hypotheses regarding the origins of autism have been made. Autism is now defined as a behavioural syndrome resulting from interconnected factors, of which some may be of genetic origin. The authors present the case of a child who seemed to be autistic and use a clinical observation to enlighten questions raised by autism. This article illustrates the evolution of an autistic child, Alain, who needed special efforts and an emotional investment from the teacher. The teacher had to adapt his teaching method to the child’s needs. Forgetting models and approaches, Alain’s teacher managed to teach him things that seemed impossible to teach at the beginning. She established a plan and got deeper in the relationship. Regarding Alain’s case, it seems fundamental to consider autistic children as unique persons. Despite the key symptoms that we can find in many cases, these children are all different. Being more involved helped Alain to begin to see that he was a child, just a simple child, who could live among the others and not on the fringes. Autism has been the subject of several debates about the best approach and the best single theory to understand it: but that is ideology. Autism is too complex to be reduced to one and only one approach. A unique approach will not allow us to understand the mystery of autism.