The origin of this thesis is a question of the differentiated use of psychotropic psychotropic medicines in contemporary societies and the question of the borders between drugs and psychotropic medicines, mental pathology and suffering, therapeutic and comfort (Ehrenberg, 1991, 1995, 2000; Ehrenberg and Mignon 1998). The central assumption is: the social and individual effects of psychotropic use depend more on the social relationships in which they are part of the biochemical qualities of the substances. These social relations are the result of a particular articulation between the representations of substances, the contexts of use and the expected purpose of use. They involve norms, values and beliefs, media media as a picture tank and imagination as a psychic function (Durand, 1998). To explore this idea, we studied the use of a natural hallucinogen (Ayahuasca) in the context of traditional Peruvian Amazonian medicine. The ritual use studied and the translations of psychic states following ingestion call on the notions of health, mental illness and normativity. The latter is a valuable anthropological and sociological indicator of a particular dialogue between subjectivity and sociality. During our analysis work (semi-directed interviews with healers and users of Ayahuasca), we show how the attribution of meanings to a specific psychic state (the following ingestion) is normality, while it refers to pathological forms recognized by psychiatry. The consciousness modification following ingestion of the substance is a temporary state, framed by ritualisation. The significance conferred on this particular experience (hearing voices, being attacked by monsters for example), indicates contact with an invisible dimension of the real. The originality of this thesis lies in the demonstration of mechanisms and processes that make a state of strange and alteration to itself a structuring, therapeutic and social link experience. The mechanisms for regulation and the efficiency of use are essentially sacred: the central device by which the interiority and externalism fills the culturally anchored and phenomenologically attested with an invisible dimension of the real. The use of Ayahuasca is in this way a social fact of a social nature, and simultaneously a social fact of a psychic nature. It allows specific symbolic manipulations of the categories of good and evil, of real and of imagination by and in a life of the sacred. He also participates in the formation of an individual ethic embedded in social ethics: self-concern is indissociable to and for others. Based on this analysis and the theoretical considerations on the fundamental role of imagination, imagination and sacred in all societies (Bastide, 1975, we reconsider the use of psychotropic use in contemporary Western societies in their joint action with the question of normativity. On the one hand, the naturalization of mental illness by the pathological designation based on biochemical etiology (to any biochemical disorder corresponds to a psychic disorder) evacuates the social dimension and to some extent participates in a lock-up of the subject on pure subjectivity marked by the borders of individuality. The issue of health and mental pathology cannot be understood without integrating this social dimension and the central role of the associated values and beliefs. Normality and abnormality are in this context individual facts of a social nature. On the other hand, the banalization of psychotropic drug use, the permanence and variability of drug use would indicate forms of resistance, or, on the contrary, accommodations for the eradication of the sacred and invisible. They would be the expression of a particular relationship to life and death in which the biomedical field (knowledge and therapeutic practices) has, to some extent, substituted for philosophy and religion, to mediate between visible and invisible, known and unknown, health and disease, normality and abnormality. Keywords: psychotropic, sacred, therapeutic, care, imaginary, imagination, symbolic, ritual, beliefs, traditional medicine.