Laughter
Marc cuts down Serge's purchase of the painting by Antrios as soon as he sees it with his arrogance and laughter. The imagery is cutting, as Serge isn't merely showing his friend a painting, but rather introducing him to a piece of himself that he sees in his purchase, and Marc is completely diminishing it.
Unity
Serge and Marc have had a common love of art and it represents how their tastes serve their relationship. So the imagery of two men cutting one another down over an object's subjective interpretation reveals that their need to be right has outweighed their love for one another.
Disappear
Marc's final words of the play are him describing Serge's painting. He says that is represents a man moving across a space and then disappearing. The imagery is haunting at the reality of our lives being utterly insignificant in the grand scheme of it all.
Piece of . . .
Marc describes Serge's purchase as a piece of white garbage. The imagery created by this is incredibly vivid as it calls to mind exactly the texture, smell and imagery of what Marc believes Serge's new purchase to be.
