In 1953 two major books came out that were to contribute greatly to the understanding of the Ghent Altarpiece – Paul Coremans’s L’Agneau Mystique au laboratoire and Erwin Panofsky’s Early Netherlandish Painting. Before becoming the best of friends, the scientist and the scholar had learned to know and appreciate each other. They soon realized that their different approaches – technical and art historical – were complementary. To bring about a close collaboration, they set out to organize in Brussels a seminar entirely devoted to the polyptych. It gave a team of leading experts ample opportunity to discuss the new findings and interpretations using laboratory documents and scientific imagery, before examining the altarpiece in situ. The results of these interdisciplinary moutonnements were carefully recorded but never published. They are nevertheless an inspiration and food for thought for all those who are currently involved in the research and the treatment of the Ghent Altarpiece.Papers Presented at the Eighteenth Symposium for the Study of Underdrawing and Technology in Painting, Brussels, 19-21 September 2012