Michael Rosen and Dr. Laura Wright talk to Dr Ross Wilson about how we talk about historical eras in order to define the way we live now, and how we've progressed. Ross Wilson is a historian at the University of Chichester who's written a book called The Language of the Past delving into the origins of terms about periods in history - Stone Age, mediaeval, Victorian Values - when we came up with them and why we use them. How historically accurate are they and does it matter? Producer Beth O'Dea.