Talking about Knowledge Johan van Benthem Abstract: In current studies of knowledge at the interface of logic and epistemology, philosophical positions and logical systems lore meet in new ways. This little piece, a programmatic sequel to van Benthem 2011 ("Logical Dynamics of Information and Interaction") and a prequel to Baltag et al. 2015 ("The Music of Knowledge"), adds some further perspectives and issues to this mix from dynamicepistemic logics of information and inquiry. Its aim is to show that we can have a yet richer agenda of epistemic themes, and a richer view of the interplay of logic and epistemology, when we make epistemic action a major focus on a par with knowledge or belief per se. To appear in C. Baskent, L. Moss & E. Pacuit, eds., "Rohit Parikh Volume", Outstanding Contributions to Logic, Springer.