It goes without saying that no short lecture series and no book, especially of this limited size, can possibly do more than scratch the surface of a vast subject such as world rock art, a corpus which comprises many thousands of sites and millions of images, and which spans the entire globe and tens of millennia. What I propose to do here, therefore, is to make this volume a kind of successor and complement to my earlier work for Cambridge University Press, the Cambridge Illustrated History of Prehistoric Art (1998), by focusing to a large extent on information, discoveries, and debates which have arisen since its appearance, as well as on rock art from areas which were neglected in that volume.

Those who attended the original lectures will find some major changes in content – this is inevitable both because of the passage of time and, especially, because the talks were picture-led and heavily illustrated, whereas in the written format the emphasis must be on text. Nevertheless, the subject matter of each chapter remains essentially what was conveyed in the six lectures.

In recent years some specialists have become so disillusioned about the chances of producing a valid or verifiable interpretation of any prehistoric rock art that they prefer to focus on techniques, chronology, style, and so forth. At the other extreme, there are specialists who are incredibly optimistic – one example is Emmanuel Anati, who has recently declared that he believes that we will eventually be able to read rock art simply because prehistoric people could read it! In one of a series of programmes called The Drawings on the Wall, broadcast on BBC Radio 4 in early 2008, the Italian researcher referred to the problems involved in interpreting rock art as follows: ‘[the] most likely outcome is a method in which you can read the rock art like you can read a foreign language. There is a big difference in favour of rock art that this writing can be read in any language. This language was understood 10,000 years ago. Why shouldn't it be understood today? It is just getting into the right state of mind. You have to find the right way to read it’.