Because it is devoid of any demonstration, William Jones’discovery of the relationship between the different Indo-European languages constitutes an enigma for the history of linguistics and other sciences of language. The discrepancy between results which seem to anticipate on 19th century comparative grammar and an apparently archaic conceptual construction which aims to tack on the confirmation of the tale from Genesis to the concepts inherited from the grammar of the Classical age by linking the Hindus to Noah’s descendance can only be explained by the incorporation, by the English orientalists, of techniques of morphological analysis from Indian grammar. In order to understand the historical conditions that made such an epistemological hybridity possible, a hybridity that also needs to be understood as a confrontation between Christianity and Brahmanical knowledge, this paper compares the two systems which provided the context for the production of knowledge about the societies and the religions of India during the 17th and 18th centuries : Christian missions and the British colonial Empire.