 More importantly, the very idea that formal rules can be applied to areas outside of logic or mathematics may itself have been catalysed by Europe's contact with the work of Sanskrit grammarians.Pāṇini, and the later Indian linguist Bhartrihari, had a significant influence on many of the foundational ideas proposed by Ferdinand de Saussure, professor of Sanskrit, who is widely considered the father of modern structural linguistics and with Charles S. Peirce on the other side, to semiotics, although the concept Saussure used was semiology.Saussure himself cited Indian grammar as an influence on some of his ideas.