we're all in the big glass
This of course is Marcel Duchamp's "The Bride Stripped Bare by Her Bachelors, Even (The Large Glass)," 1915-23. The materials include oil, lead foil, lead wire and (say the people at the Philadelphia Museum of Art) "dust" also. All on (or in) two glass panels. A box of papers that are the drawn plans and other writings about the project, by Duchamp, is displayed nearby. (The box makes me think of Robert Granier's Sentences, and although I'm no expert on Sentences I have to guess that Grenier was in part thinking of and positively influenced by these sorts of boxes-of-papers-as-art projects Duchamp undertook.)
Bride Stripped is hard to photograph, even by good photographers (I am not that). I try to see it at least once a year at the PMA and always try my hand at snapshots. This time I didn't wait for people also looking at the work to move away and decided just to let them be part of the transparency. Without knowing this as a matter of fact, I'm certain that Duchamp would want them to be included in the view.