Large bottles of cornichons and mustard, sharp knives and a bag heaving with ciabatta gave me a clue. "I think they're our snacks," I said to my husband. He smiled and walked into the third and fourth gallery: one housing a vast display of champagne bottles in silvery ice buckets, the other an entire gallery of beer on tap. One by one, it dawned on guests that we could participate, eat and drink the display, become part of the artwork.