Van Gogh versus rock art. Both priceless. But one sits behind glass in a temperature controlled museum heavily guarded. The other is left out in the open, subject to vandals, insects and inclement weather. Professor Tacon has spent the last three decades travelling extensively to remote areas of Australia to unravel the stories of our past and save them for our future. rofessor Tacon knows that time is running out to safeguard many of these ancient survivors.