The paper presents an analysis of engagement markers in the Lectures on Physics by eminent scientist and Nobel prizewinner R. P. Feynman, based on K. Hyland's model of interaction in academic discourse as stance and engagement. The Lectures were taught at the California Institute of Technology during 1961-63 and, having been turned into a textbook, are widely used by Physics students even today. It is argued that the Lectures owe their lasting popularity not only to the simplicity of explication, but also to Feynman's masterful use of interaction devices, particularly reader pronouns, directives, questions, references to sharedness and personal asides. Reader pronouns are analysed in comparison with the MICASE-based reference corpus, with the most common you and we-clusters being identified. It is established that reader pronouns, directives and questions in the Feynman's Lectures on Physics mostly perform the functions of anticipating possible objections, eliciting prior knowledge, focusing students' attention, stimulating their thought and creativity, while references to sharedness and personal asides serve to strengthen the lecturer's communality with the audience, particularly through the use of humour. We draw the conclusion that Hyland's taxonomy of engagement markers can be applied to spoken academic discourse in its entirety and can be particularly useful for the description of interactive styles of acknowledged scientists, supplementing depersonaliased corpus research in search for best practices in pedagogy.