Transcript of the keynote speech by French sociologist Michel Grossetti at the 2024 Frognet conference. In this talk, he reflects on his academic background, and describes the steps that led him, starting in the late 1980s, to discover social network analysis, an approach he has continued to explore and develop throughout his research. Grossetti highlights the value of this framework, with a particular focus on two case studies: local systems of action and the links between science and industry.