Abstract
According to Poincaré, science concerns crude facts [faits bruts] and relations. Considering that the crude fact is perceived through the body, (senses and movements), Poincaré contends first of all (against the opinion of Le Roy, who believes that the scientist freely creates the fact) that the scientist does not create the crude fact but "creates the scientific fact" (Poincaré, 1958 [1905], p. 116). The achievement of a scientific fact from a crude fact is a question of translation which occurs as a result of a mutation of language: "The scientific statement is the translation of the crude statement into a language which is distinguished above all from common German or French, because it is spoken by a very much smaller number of people" (Poincaré, 1958, p. 119). This translation obeys the criteria of "convenience": "The scientific fact is only the crude fact translated into a convenient language" (Poincaré, 1958, p. 120).