Previously, linguists had thought of language as learned cultural behaviour: chaotically variable, inseparable from social life and therefore beyond the remit of natural science. The Swiss linguist Ferdinand de Saussure, for example, had defined linguistics as a branch of 'semiotics', this in turn being inseparable from anthropology, sociology and the study of man-made conventions and institutions. By picturing language instead as the natural mechanism of 'digital infinity', Chomsky promised to bring scientific rigour to linguistics as a branch of strictly natural science.